The UN Security Council is to consider a new resolution against Syria - but has faced immediate opposition from Russia, whose UN ambassador said the new draft "crosses our red lines".
Vitaly Churkin said the new Arab and European proposal, which was submitted officially by Morocco for a vote which its supporters hope will take place next week, was trying "to impose an outside solution" to the conflict in Syria.
" The Arab League may have its ideas where political dialogue should go," he said.
"Certainly they are free to express those ideas but the Security Council should not be a tool to impose specific solutions on countries, including, in this particular case, Syria."
Along with China, Russia exercised its veto in October following the last European draft which would have meant "targeted measures" against Syrian President Bashar al Assad.
Gulf Arab states and Turkey were due to meet in Istanbul, where they hope to sway international actors into supporting further action - particularly following the Arab League's announcement last week that Mr Assad should allow his deputy to take the reins in order to restore stability.
Britain, which crafted the resolution with France and consultation from Qatar, Morocco, Germany and the United States, emphasised its commitment to the resolution, with the UK's ambassador to the UN saying "the time has come" to support the Arab League.
The new text "fully supports" the Arab League plan and "encourages" all states to follow sanctions adopted by the pan-Arab bloc last November, but contains no mandatory action, or arms embargoes.
"You should not be fooled by those who are claiming there are all sorts of other things in the text, trying to refight battles over Libya," Ambassador Mark Lyall Grant said, also dismissing claims that regime change was at the heart of the new draft.
"We want, as do the Arabs, a unanimous resolution. Frankly, the time has come when we should be supporting the Arab League."
Russia's exception to the resolution concerns fears over an arms embargo which would threaten its multi-billion dollar arms trade with its Cold War ally.
Earlier this month, Moscow was criticised amid reports of an arms shipment to the troubled Arab country.
The UN slammed the shipment, and while not mentioning Russia by name, Mr Lyall Grant said: "It is glaringly obvious that transferring weapons into a volatile and violent situation is irresponsible and will only fuel the bloodshed."
According to the Syrian Observatory for Human Rights, the death toll in recent days has topped 100, as Aleppo - the country's second city and until recently not a scene of mass protest - reported its first protest-related deaths with a car bomb in the north of the city.
Fears of sectarian divides and civil war intensified after a Sunni family of 11 were reportedly executed in their home by a group of Alawi militiamen.
"It is racial cleansing," one Homs resident said. "They are killing people because of their sect."