Members of the UN Security Council will meet early Saturday in a bid to pass a resolution condemning the violent repression in Syria, amid firm opposition from Russia, a diplomat said.
The vote will follow charges that Syrian forces killed more than 200 civilians, including women and children, in a "massacre" in the central city of Homs.
The Syrian Observatory for Human Rights said 138 of the fatalities were caused by mortar fire in the Al-Khalidiya district of Homs, which has become a flashpoint of the 10-month revolt against the regime of President Bashar al-Assad.
The UN meeting also comes on the same day that US Secretary of State Hillary Clinton is due to hold face-to-face talks with Russian Foreign Minister Sergei Lavrov, amid a fresh American push for passage of the resolution.
"It is the same text that's going to a vote," the diplomat said on Friday, referring to the draft resolution sent to the council's 15 members the previous day.
The council is expected to meet between 9:00 am and 11:00 am local time (1400-1500 GMT), the diplomat said.
The resolution faces an uncertain fate, as Moscow had maintained its opposition to a tougher draft resolution authored by Western powers and the Arab League.
Russia also said Friday it could not support a new draft in its current form, which states the council fully supports an Arab League plan to facilitate a democratic transition, but leaves out explicit references to calls for President Bashar al-Assad to step down.
"Some of our concerns and the concerns of those who think the same as us have been taken into consideration but all the same this is not enough for us to be able to support it in this form," deputy foreign minister Gennady Gatilov said.
The Security Council has yet to adopt a resolution on Syria despite 10 months of violence that has left more than 6,000 people dead, rights groups estimate. An earlier draft was blocked in October by both Russia and China.
Clinton held what her spokesman described as "constructive" talks by telephone with Lavrov over the draft, and the pair were due to meet in Munich, likely ahead of the UN vote.
"You can be sure that Syria and the discussions at the UN will be one of the issues there, among many," a senior State Department official said.
The new draft backs a January 22 Arab League request that Assad transfer power to a deputy and a government of national unity within two months but does not call on him to step down, according to a copy obtained by AFP.
Instead, it calls for a "Syrian-led political transition to a democratic, plural political system ... including through commencing a serious political dialogue between the Syrian government and the whole spectrum of the Syrian opposition under the League of Arab States' auspices, in accordance with the timetable set out by the League of Arab States."
The draft also "condemns all violence from whatever source and ... requires that all parties in Syria, including armed groups (opposition), immediately cease all violence or reprisal."
The latest attempt at consensus emerged after hours of talks stalled in the Security Council, with Moscow leading the opposition to the tougher draft resolution authored by Western powers and the Arab League.
Diplomats said the new draft takes into account concerns by Moscow, a staunch Damascus ally.