(CNN) -- Three U.S. lawmakers traveled to Baghdad to meet with Iraqi leaders over the worsening crisis in Syria amid reports that Iraq is allowing Iran to use its airspace to deliver weapons to embattled President Bashar al-Assad's forces.
Al-Assad has been under intense international pressure to step down and end a civil war that began 18 months ago.
Here are the latest developments for Thursday:
Stern warning part one: From the United States
Iraq disputes reports that it is allowing Iran to deliver weapons to Syria. The denial follows word that several U.S. senators traveled to Baghdad to warn against such an act.
"Iraq will not allow any country to supply weapons or fighters through its lands or airspaces to the conflicted parties in Syria," government spokesman Ali al-Dabbagh said Thursday.
A day earlier, a U.S. State Department spokesman said that "Iranians are doing little to hide their hand" in supporting the Syrian regime.
"And so we've expressed some concerns to our Iraqi partners, and Iraq has taken steps in the past to meet their international obligations," Patrick Ventrell, an acting deputy spokesman, said Wednesday.
"... It's something that's a matter of ongoing discussion between us and our Iraqi partners."
Ventrell declined to comment on whether the United States is convinced that Iran is transporting weapons to Syria through Iraqi airspace. "This is an issue we've raised with our Iraqi partners, I'm not going beyond that," he said.
But Ventrell's comments came as news broke that U.S. Sens. John McCain of Arizona, Joe Lieberman of Connecticut and Lindsey Graham of South Carolina were meeting with Iraqi Prime Minister Nuri al-Maliki and Foreign Minister Hoshyar Zebari.
Al-Dabbagh declined to detail the meetings, which were confirmed by Lieberman and McCain in posts on Twitter.
Lieberman said Washington must "make real our strategic partnership" with Baghdad, especially as the Syria crisis worsens," according to a Twitter post. He also called for a no-fly zone in Syria.
Shiite-dominated Iran is closely allied with Syria's Alawite minority-controlled government. Al-Assad belongs to the Alawite religious group, an offshoot of Shiite Islam.
Stern warning part two: From Russia
Russian President Vladimir Putin warned Thursday that the West's position on the Syrian crisis is "fraught with dire consequences."
The comments -- made in an interview with the state-run RT news channel -- came as tensions between Russia and the United States, the European Union and members of the Arab League have mounted over the Syrian crisis.
"Today some want to use militants from al Qaeda or some other organizations with equally radical views to accomplish their goals in Syria," Putin said in the interview. "This policy is very short-sighted and is fraught with dire consequences."
Putin compared alleged Western funding of militants to topple al-Assad to U.S. support for Afghan rebels after the 1979 Soviet invasion.
"At that time, our present partners supported a rebel movement there and basically gave rise to al Qaeda, which later backfired on the United States itself," he said.
Russia -- a key trade ally with Syria -- and China have blocked any international efforts at armed intervention in the United Nations Security Council.
"How come Russia is the only one who's expected to revise its stance? Don't you think our counterparts in negotiations ought to revise theirs as well?" Putin said during the interview.
"Because if we look back at the events in the past few years, we'll see that quite a few of our counterparts' initiatives have not played out the way they were intended to."
The Syrian Foreign Ministry condemned calls by Egyptian President Mohamed Morsy for al-Assad to leave power and for Syria to enter a transitional phase.
"Morsy has made it clear and beyond any doubt that his statements reflect the views of a group that has no relevance to the real common history of the two peoples of Syria and Egypt," the Foreign Ministry said in a statement released Thursday.
Morsy made the comments Wednesday while addressing a meeting of Arab League foreign ministers in Cairo.
Syria accused Morsy of participating in a "media incitement" aimed at fueling the violence that al-Assad's government blames on armed terrorists bent on destabilizing the government.
Al-Assad has refused to acknowledge the civil war that the opposition claims has killed more than 23,000 people.
In the statement, the Syrian Foreign Ministry said Morsy was no different from the leaders of other governments "that support the terrorist armed groups with money, weapons, training and shelter, and that make them partners in the Syrian bloodshed."
Morsy's support of the Syrian opposition reflects his solidarity with the people who took to the streets during the Arab Spring, the popular label for the pro-democracy movements that swept across the Middle East and North Africa last year.
Another bloody day
At least 134 people were killed Thursday across Syria, according to the opposition Local Coordination Committees of Syria.
Among the dead were 79 people in Damascus and its suburbs, where fighting has reportedly raged in recent weeks as rebels attempt to wrest control of portions of the capital from government forces, the LCC said.
Shelling was reported in the flashpoint Damascus neighborhood of Tadamun as well as in suburban Bebila.
Another 58 people drowned as they tried to flee by boat to Turkey, the LCC said.
At least 258 people died in fighting across Syria on Wednesday, it said.
CNN's Saad Abedine, Moni Basu, Ash Gallagher and Mohammed Tawfeeq contributed to this report.