Damascus (CNN) -- U.N. inspectors in Syria face a race against time to get to the site of an alleged chemical weapons attack to gather vital evidence, but the big question Friday was whether red tape would prevent that.
Since Friday was not a working day in Syria, government offices were closed and many government officials were off. Syria's heavy bureaucracy may also mire the progress of the international demands for access.
The U.N. team is in Syria to examine previous claims of chemical weapons use at three unrelated sites, so it needs special permission to go to the scene of the latest alleged attack in Ghouta, a rebel stronghold on the outskirts of the capital.
The area, which is contested, appeared to be the target of shelling again Thursday night.
U.N. Secretary-General Ban Ki-moon said Friday that allegations the Syrian regime used chemical weapons should be investigated immediately, adding there was "no time to waste" in getting the team into Ghouta.
He said he had called on the Syrian government to allow the team access and was sending U.N. High Representative for Disarmament Affairs Angela Kane to Damascus to press the case for an urgent investigation.
"I can think of no good reason why any party -- either government or opposition forces -- would decline this opportunity to get to the truth of the matter," Ban said.
UK Foreign Secretary William Hague suggested the delay in granting access was suspicious. "It seems that the Assad regime has something to hide," he said.
"This is not something that a humane or civilized world can ignore. Our priority is to make sure the world knows the facts of what has happened, and that means the U.N. team that is in Damascus, only 20 minutes away, being able to get there and to investigate."
Time is of the essence, Hague added, since the evidence will deteriorate "over a matter of days."
The Syrian government has denied using chemical weapons.
Syrian rebels promise access
Russia's Foreign Ministry appeared Friday to accuse the Syrian opposition of blocking U.N. access to the site.
"Signals from the opposition, including those of its readiness to ensure the safety and effective work of U.N. experts on territory controlled by its militants, which is so needed today, are not being heard," it said in a statement. "This directly contradicts an objective investigation into allegations on possible cases of chemical weapons use in Syria, which is what many countries are calling for and what Russia is calling for."
The ministry earlier Friday said that Foreign Minister Sergey Lavrov had called for both the Syrian government and opposition to allow access, in a conversation with U.S. Secretary of State John Kerry.
On Wednesday, the ministry had seemed to imply that the opposition was responsible for the use of chemical weapons, issuing a statement saying that an "improvised missile was launched from the positions occupied by militants" and that an "aggressive information attack" was designed to fool the world into believing that the Syrian regime was responsible.
On Friday, leaders of the Syrian National Coalition, an umbrella opposition group, told reporters in Istanbul that the opposition and leaders of the Free Syrian Army are "fully committed" to helping the U.N. inspectors reach all locations where chemical weapons were allegedly used.
"We hereby assure the U.N. inspectors, the U.N. secretary general and all members of the United Nations that we will ensure the safety of the U.N. inspectors' team," said spokesman Khaled al-Saleh.
"However, it is very critical to get that team into the area that was just hit in less than 48 hours. The clock is ticking, we want to see those inspectors and we believe that the evidence will show who used these chemical weapons against innocent civilians."
Al-Saleh said that medical teams in the area hit administered 25,000 shots of atropine -- a medication used to treat people exposed to the nerve gas sarin -- after the attack, and that the toll would have been much higher if that had not been done.
Syrian National Coalition Secretary General Badr Jamous said that samples had been obtained from the area -- which he said had been besieged by government forces for months -- and were being sent outside Syria for analysis.
Jamous detailed the firing of rockets -- some with chemical warheads and others conventional weapons -- early in the morning into what he said was a heavily populated civilian area.
More than 1,300 were killed, most of them as a result of the use of chemical weapons against civilians, said Saleh -- all while the U.N. inspection team was only 10 kilometers (6 miles) away.
Jamous said the attack also injured more than 5,000 people.
The chemical component used has not yet been identified, Jamous said, but the number of casualties involved means the U.N. team should be moving in urgently to check the scene.
Graphic video footage showed rows of bodies without apparent injury, as well as people suffering convulsions or apparently struggling to breathe.
CNN could not immediately verify where or when the videos were recorded, and could not authenticate the number killed or injured.
Obama: 'Big event of grave concern'
In an exclusive interview with CNN's "New Day" anchor Chris Cuomo, U.S. President Barack Obama said preliminary signs point to a "big event of grave concern."
"It is very troublesome," he said. "That starts getting to some core national interests that the United States has, both in terms of us making sure that weapons of mass destruction are not proliferating, as well as needing to protect our allies, our bases in the region."
U.S. military officials have updated options for a forceful intervention in Syria, a senior defense official tells CNN. The Joint Staff and U.S. Central Command last conducted a major update of options in April, in response to bipartisan pressure from congressional Republicans and Democrats.
Target lists for possible airstrikes were updated, including government buildings and military installations, but Syrian President Bashar al-Assad's forces and equipment "continue to move," and thus require flexibility in planning, the official said.
The planning, meant to give Obama "a current and comprehensive range of choices," also included updates on the potential use of cruise missiles, which would not require U.S. pilots to enter Syrian airspace, the official said.
No decision was made at a national security meeting Thursday at the White House, and no formal determination has been made on whether the Syrian government used chemical weapons, the official said.
On Friday afternoon, reporters asked White House deputy press secretary Josh Earnest about Syria.
"We've said the assistance we provide to the opposition is on an upwards trajectory, expanding in scope and in scale. We have long said that all options remain on the table when it comes to Syria.
"The president has indicated clearly that he does not foresee a situation in which American boots on the ground would be in the best interest of U.S. national security. But ultimately, that is the criteria he will use when he evaluates the proper course of action in this situation."
When reports of a possible chemical attack came in on Wednesday morning, U.S. Ambassador Samantha Power called for immediate consultations with the Security Council. The U.S. mission sent a joint letter to Secretary-General Ban, along with 36 other countries, that evening asking for an immediate investigation, a source with the mission told CNN.
Power was out of the office on personal travel at that time, but returned to her New York office on Friday, the source said.
The images of victims of the alleged attack, including many children, are "heartbreaking and sickening," Ban has said.
"Any use of chemical weapons anywhere, by anybody, under any circumstances, would violate international law. Such a crime against humanity should result in serious consequences for the perpetrator."
Ban said the situation in Syria, where rebels have been fighting al-Assad's forces for more than two years, continues to worsen. The death toll has surged past 100,000, he said.
In a statement Friday, European Union foreign policy chief Catherine Ashton backed the United Nations' request for "a thorough, impartial and prompt investigation into these alleged chemical attacks."
"The international community must now urgently show a united face and ensure that a credible and thorough investigation can be carried out," she said.
Iranian President Hassan Rouhani condemned the use of chemical weapons, particularly in Syria, Iran's state-run news agency, IRNA, said Saturday.
"The conditions ruling Syria, in which a large number of innocent people are wounded or killed by the chemical elements, are regrettable," he said, according to semiofficial news agency, Fars.
A million child refugees
Two U.N. agencies announced Friday that the number of child refugees from Syria has passed a landmark threshold, with 1 million forced to flee during the conflict. They make up half of all refugees from the country.
About 740,000 of the children registered are younger than 11, U.N. children's agency UNICEF said. Most have arrived in Lebanon, Jordan, Turkey, Iraq and Egypt, with some families also heading to North Africa and Europe.
"This one millionth child refugee is not just another number," said UNICEF Executive Director Anthony Lake. "This is a real child ripped from home, maybe even from a family, facing horrors we can only begin to comprehend."
Inside Syria, about 7,000 children have been killed during the conflict, according to the Office of the High Commissioner for Human Rights, while another 2 million children have been internally displaced.
U.N. High Commissioner for Human Rights Antonio Guterres told CNN there was the risk of a lost generation in Syria and many of the children caught up in the conflict are showing a high level of trauma.
"I've seen many that do not speak any more, I've seen some with broken sleeping, that have enormous difficulties, some with behaviors that are very challenging and very strange," he said.
The apparent presence of many small children among the victims of Wednesday's alleged attack will add to concerns about the safety of Syria's most vulnerable citizens.
An al-Assad government spokesman said any claims it used chemical weapons are "illogical and fabricated."
Syrian Information Minister Omran Zoabi told state TV the claim was timed by the opposition to coincide with the U.N team's visit and came as government forces were making gains on all sides against the rebels.
In the streets of government-controlled Damascus, many people said they do not believe the government resorted to the use of nerve agents. The CNN team is in Syria is on an officially approved trip.
"The government would never use chemical weapons because Bashar al-Assad is part of the country, he grew up here, they are Syrians," one man told CNN.
Another said he believed that if anyone was hit, it was members of the rebel Free Syrian Army.
Residents confirmed that there appeared to be a massive military operation under way early Wednesday, with warplanes dropping bombs and artillery firing for hours.
Staff at the Mezzeh University hospital told CNN they received many casualties Wednesday from the area allegedly hit by the attack. But, they said, the casualties showed no signs of having been subjected to chemical agents.
However, experts who have viewed footage purportedly from the scene say it indicates that some form of chemical seemed to have been used.
The U.N.-Arab League envoy to Syria, Lakhdar Brahimi, says he believes the recent violence in Ghouta emphasizes the need for a political settlement between the Syrian government and opposition, his spokeswoman Khawla Mattar told CNN on Friday.
"The human loss is unacceptable and we have to do something about getting all parties, particularly the two Syrian sides ... to the Geneva II (peace talks) sooner than later," Mattar said.
A previous meeting of world leaders aimed at taking steps to bring peace to Syria took place in Geneva, Switzerland, just over a year ago. No date has been set for a second Geneva conference, originally expected in June, but Ban said he was working with Kerry and Lavrov to convene it "as soon as possible."
There is no indication when the U.N. inspection team, currently in Damascus, will be able to travel to the site of the alleged attack, Mattar added.
The allegations of chemical weapons use spurred calls Thursday for the United Nations to act.
Turkey's foreign minister, Ahmet Davutoglu, said that "all red lines" have been crossed in Syria and that the United Nations cannot be indecisive about chemical weapons attacks there.
His French counterpart, Laurent Fabius, said force must be used if the claims of chemical weapons use were proved, although he ruled out the use of ground troops.
Their comments came after the U.N. Security Council held a short-notice briefing late Wednesday to discuss the situation. Russia and China -- consistent allies of the Syrian government -- reportedly blocked a formal resolution.
Obama has directed the U.S. intelligence community to urgently gather additional information to try to assess whether chemical weapons were used Wednesday, State Department spokeswoman Jen Psaki said Thursday.
At this time, she said, the United States is unable to "conclusively determine" chemical weapons use, but is focused on trying to nail down the facts, along with its international partners.
Psaki said, as she has before, that if reports of chemical weapons use prove true, the president has a range of responses available.
Later, a senior defense official told CNN that "the military continues to refine options for Syria to be prepared for whatever the president might request down the line."
U.N. High Commissioner for Human Rights Navi Pillay said the matter is "of utmost urgency" and the "allegations are exceptionally grave."
Pillay urged the government and opposition to allow investigators "to examine the site of the alleged attacks without any delay or obfuscation."
Meanwhile, a U.S. defense official said Friday the United States has added one more destroyer to the eastern Mediterranean fleet.
The USS Ramage arrived to replace the USS Mahan, but the Mahan is going to stay around a bit longer, so temporarily there will be four in the fleeet. The USS Gravelly and USS Barry are still there.
These ships are all equipped with the Tomahawk Land Attack Missiles, a long-range subsonic cruise missile used to attack land targets.
CNN's Frederik Pleitgen reported from Damascus and Laura Smith-Spark wrote and reported in London. CNN's Chris Lawrence, Hamdi Alkhshali, Samira Said, Arkady Irshenko, Alla Eshchenko, Richard Allen Greene and Becky Anderson contributed to this report.