(CNN) -- Syrian artillery fire echoed throughout the embattled city of Homs on Monday, with a human rights group reporting nearly 100 more civilians killed around the country.
Most of the deaths occurred in Homs, where an opposition activist known as "Omar Shakir" said more than 60 people had been killed Monday. Government troops have pounded the area since last week in the latest attempt to crush an 11-month-old popular uprising.
"More than 500 shells have come down on us since the morning, targeting homes, protest places and mosques," he said. Much of the bombardment targeted the neighborhood of Baba Amr, where rockets, tank fire and mortars were hitting "from all sides."
A mosque was hit by more than 10 shells, destroying a large part of it as well as surrounding homes, he said. He some of the wounded are likely to die due to lack of proper care, while some survivors have suffered crippling or disfiguring injuries.
"There is no bread, no medication and no nutritional supplies, and as we mentioned in our last report, a field hospital was targeted and we lost a number of our medical crew," he said. "There is no form of communication inside the area, and any moving thing is targeted by snipers surrounding the area."
The violence came two days after China and Russia vetoed a U.N. Security Council draft resolution that would have demanded President Bashar al-Assad stop the violence and seek a solution to the crisis. The decision drew a bitter rebuke from "Zaidoun," a Damascus-based opposition member who spoke to CNN's "Anderson Cooper 360."
"I want really to thank the entire world for watching us so silently," he said. "We are getting killed every moment. We are not able even just to get some basic medicine to injured people. Children are really hungry. I swear, children are hungry. No power, no fuel. It's too cold."
The London-based Syrian Observatory for Human Rights said 98 civilians were killed nationwide, most of them in Homs. Another 13 died in and around Idlib, while 15 were killed in the Damascus area and one person died in the village of Mari, near Aleppo.
But Andrew Tabler, a Syria analyst at the Washington Institute for near East Policy, told CNN's "Erin Burnett OutFront" that government troops are being worn down in what appears to be "a game of whack-a-mole" with a growing insurgency.
"The army can't be everywhere at the same time, so then it has to withdraw, and then the armed opposition comes up somewhere else," he said. "This is wearing down Assad's forces and is slowly putting the Syrian conflict out of control."
Syria's state-run TV said Monday that "armed terrorist groups" were attacking citizens and members of law enforcement in several cities, including Homs, Idlib, and the Damascus suburbs. CNN cannot independently confirm opposition or government reports from Syria because the government has restricted journalists' access to the country.
"Zaidoun" dismissed the "terrorist" explanation, telling CNN, "I don't know any armed thug in the world who owns tanks.
"It was the tanks of the Syrian army and the guns of the Syrian army. I saw the army itself killing their own people," he said.
Western powers, meanwhile, stepped up their criticism of the al-Assad regime and of its supporters in the Security Council. Speaking to the House of Commons on Monday, British Foreign Secretary William Hague said Moscow and Beijing were backing "a doomed regime as well as a murdering regime."
"They chose to side with the Syrian regime and implicitly to leave the door open to further abuses," he said.
"Such vetoes are a betrayal of the Syrian people," he added. "In deploying them, they have let down the Arab League; they have increased the likelihood of what they wish to avoid in Syria -- civil war -- and they have placed themselves on the wrong side of Arab and international opinion."
Hague said his country called its ambassador home for consultations, while the United States closed its embassy in Syria and pulled out remaining staff after the Syrian government refused to address its security concerns, the U.S. State Department said.
Britain also demanded that Syria protect the British Embassy in Damascus and called Syria's ambassador for a meeting at the Foreign Office. Hague vowed that Britain and other countries will remain focused on pressuring Syria on numerous fronts, "undeterred by Saturday's vote."
Chinese and Russian representatives said they want the violence to end and to see dialogue among Syria's opposition factions. On his way to Damascus for talks with al-Assad, Russian Foreign Minister Sergey Lavrov said Western states "are trying to obscure the developments with hysterical statements on Russia's veto of the Syria resolution," according to comments carried on the Foreign Ministry's Twitter page.
"The UNSC's attempt to force the Syrian regime to stop the violence without the same for the armed groups shows support for one side," Lavrov said. He added that it was "disrespectful" for council members to bring the resolution up for a vote "despite our request to wait for Russia's report after its visit to Damascus."
U.N. Secretary-General Ban Ki-moon's office issued a statement saying he "is appalled" by the violence. "The lack of agreement in the Security Council gives no license to the Syrian authorities to step up attacks on the Syrian population. No government can commit such acts against its people without its legitimacy being eroded," he said.
"The secretary-general calls upon all concerned in Syria and in the international community to redouble efforts aimed at stopping the violence and seeking an inclusive Syrian-led political process, in accordance with international law, that respects the will and legitimate aspirations of the Syrian people to a democratic and pluralistic political system."
And Arab League Secretary-General Nabil Elaraby condemned Syria's heavy bombardment in some areas that led to scores of deaths.
"We are following the developments anxiously and extremely disturbed about the situation on the ground in Syria, especially in Homs and the suburbs of Damascus, in the escalation of the military operation and the usage of heavy artillery against the civilians," Elaraby said in a statement.
He called it "an obvious breach" of international humanitarian law and Arab League human rights commitments, according to the statement.
Protesters and rebel fighters are demanding an end to al-Assad's rule and the beginning of true democratic elections. Al-Assad has been in power since 2000; his father, Hafez, ruled Syria for three decades.
U.N. officials have said an estimated 6,000 people have died since protests began nearly a year ago. The Local Coordination Committees said at least 7,339 people have been killed.
Russia and China say they support an end to the violence, but did not agree with the text of the resolution, which they said would have complicated the issue and sent conflicting signals.
The two countries -- which have major trade deals with Syria -- have said they support a dialogue among factions in Syria.
On Monday, China's Ministry of Foreign Affairs rejected criticism of the country's veto.
"China does not accept the accusation. We are not selfish in our decision," the ministry said. "China does not shelter anyone. We uphold justice and take a responsible attitude. We want the Syrian people to be free from the scourge of conflict and warfare."
CNN's Holly Yan, Josh Levs, Azadeh Ansari, Jennifer Deaton, Yousuf Basil, Richard Roth, Mick Krever, Eunice Yoon and Schams Elwazer contributed to this report.