Munich: Moscow said today it had made a "quite specific" ceasefire proposal for Syria as foreign ministers gathered in Munich, hoping to revive a floundering peace process amid warnings of a "new world war".
With Syria peace talks derailed by the regime onslaught on Aleppo, the UN said 51,000 Syrians had fled the northern city this month as government forces backed by Russian bombers and Iranian fighters left the opposition there virtually surrounded.
"We made propositions for a ceasefire that are quite specific," Russian Foreign Minister Sergei Lavrov said as he sat down for talks with US counterpart John Kerry.
Moscow has refused to confirm reports that its ceasefire would take effect only on March 1, giving another three weeks to an offensive which the UN says could place 300,000 people under siege.
Observers say the bombardments on Aleppo have killed 500 people since they began on February 1.
Russian Prime Minister Dmitry Medvedev, meanwhile, warned that any move by Gulf nations to send in troops to support the rebels would risk a "new world war".
"The Americans and our Arabic partners must think hard about this: do they want a permanent war?" he told Germany's Handelsblatt newspaper.
US diplomats said that any ceasefire in the Syria conflict should be "immediate".
"This is an issue of commitments we all took, and that we have to respect," added EU foreign affairs chief Federica Mogherini.
But Russia and Iran have repeatedly labelled the rebels in Aleppo as "terrorists" and suggested there can be no settlement until they have been militarily defeated.
"Those who are outside Syria should help the peace process and not seek to impose conditions on the Syrian people," Iranian Foreign Minister Javad Zarif told Iran's state TV after arriving for the talks.
A first round of talks between the Syrian government and the opposition in Geneva collapsed earlier this month over the attacks on Aleppo.
The rebels say they will not return to talks, pencilled in for February 25, unless government sieges and air strikes end.
Hosted by Kerry and Lavrov, foreign ministers from the 17-nation Syria contact group came together late today for a meeting billed as a moment of truth for the floundering peace process.
Washington has threatened an unspecified "Plan B" if talks fail, as tension mounts with Moscow over its air campaign.