Syrian forces have again bombarded the city of Homs, leaving an extimated 50 people dead in a sustained assault on several districts.
As violence intensifies, the US announced this afternoon that it was closing its embassy in Damascus. It said all staff have left the country due to worsening security.
Catherine al-Talli of the opposition Syrian National Council told Reuters that the bombardment of Homs resumed early yesterday afternoon, killing 50.
Mr Assad's opponents say his tanks and artillery killed more than 200 people in the city on Friday night in the bloodiest incident of the 11-month-old uprising against his rule.
Reports from both activists and authorities are hard to verify because Syria restricts access for independent media.
However, the attack has been branded a "massacre" by France and "unspeakable" by US President Obama, who set the stage for intense efforts over the weekend to lobby Moscow not to block the UN Security Council resolution.
But Russia has argued that the resolution is one-sided and would have amounted to taking the side of Mr Assad's opponents in a civil war.
China also vetoed the measure, by most accounts following Russia's lead.
"Some of the voices heard in the West with evaluations of the results of the vote in the UN Security Council on the Syria resolution sound, I would say, improper, somewhere on the verge of hysteria," Foreign Minister Sergei Lavrov told reporters after meeting the foreign minister of Bahrain.
Syria is a long-serving ally of Moscow, one of the few in the region, and a customer for its arms exports.
Russia clearly still hopes to play an important diplomatic role with President Assad, and says it wants to encourage him to adopt reforms.
The opposition Syrian Observatory for Human Rights said it had the names of 29 people killed in the bombardment of Homs. Television footage showed smoke rising from buildings, with explosions echoing in the background.
"This is the most violent bombardment in recent days," said one activist in Syria who was in touch with Homs residents.
Another activist said government troops were using multiple rocket launchers in the attack.
The government denies firing on houses and says images of dead bodies on the internet have been staged.
State media said this afternoon that "armed terrorist groups" were firing mortars in the city, setting fire to tyres and blowing up empty buildings to give the impression that Homs was under fire from Mr Assad's forces.
