A meeting of more than 100 nations opposed to President Bashar al-Assad has called for United Nations-backed sanctions to force Syria into a political transition plan but refrained from a call for military action to end the 16-month conflict.
The "Friends of Syria" conference, held in Paris on Friday, closed with unanimous agreement that Assad must step down.
The meeting called on the UN Security Council to pass a resolution authorising sanctions and diplomatic action but which explicitly disallows the threat or use of armed force.
A six-point plan peace plan drawn up by Kofi Annan, the UN and Arab League's chosen envoy to Assad, has fallen flat, and violence has climbed to levels even higher than before the plan was proposed.
Members of Syria's opposition at the Paris meeting said the international community is still moving too slowly and called for a military measure to end the crisis.
The meeting came amid reports that Manaf Tlas, a Syrian general and personal friend of Assad, was travelling to Paris after defecting from his position as a brigade commander in the elite Republican Guard.
The meeting follows a gathering in Tunis and another in Istanbul, both of which called in vain for tougher action against Assad's government.
China and Russia did not attend either of those meetings, in which the United States, France, Britain, Germany as well as Saudi Arabia and Qatar gathered with a group of more than 60 nations, including most European Union and Arab League states.
On Friday, US Secretary of State Hillary Clinton urged world powers to show Russia and China they would "pay a price" for impeding progress toward a democratic transition in Syria.
"It is, frankly, not enough just to come to the Friends of the Syrian People [meeting] because I will tell you very frankly, I don't think Russia and China believe they are paying any price at all - nothing at all - for standing up on behalf of the Assad regime," she said.
"The only way that will change is if every nation represented here directly and urgently makes it clear that Russia and China will pay a price because they are holding up progress - blockading it - [and] that is no longer tolerable."
Russia hits back
Russia hit back on Friday, saying Washington's suggestion that Moscow should "pay a price" for helping keep Assad in power was "incorrect".
Deputy Foreign Minister Gennady Gatilov told Interfax news agency that Clinton's statement went against the strategy for ending the bloodshed in Syria that was agreed by world powers last Saturday in Geneva.
Russia, which is sensitive about outside interference in any sovereign state, lobbied hard against efforts by other powers at the Geneva talks to include a precondition that would have excluded Assad from a proposed national unity government.
"The statement (by Clinton) was incorrect," Gatilov was quoted by Interfax as saying. "What worries us more than anything is that such remarks go against the final document of the Geneva talks, the adoption of which was approved with the participation of the US secretary of state."
Meanwhile, activists said that scores of people in the town of Khan Sheikhoun had died on Friday during a government push to regain control the opposition stronghold.
"The Free Army withdrew from the town last night after it ran out of ammunition. Assad's army is in control of it," Abu Hamam, a rebel spokesman said. "They are burning the houses. They have burned my own house. I see the smoke covering the sky from where I am now."
Khan Sheikhoun, a town of more than 70,000 in the northern province of Idlib, straddles the western highway linking Damascus to Aleppo.
Thousands flee homes
Fighting between Free Syrian Army rebels and loyalist forces was also reported in the Kfar Souseh quarter of central Damascus after security forces attempted to stop a protest against Assad near the Nouaim Mosque. The district is home to major intelligence and secret police installations.
The United Nations has warned that thousands more people in Syria have fled their homes in the past two weeks due to heavy fighting and that food prices have tripled in parts of seven provinces where the livelihoods of farmers and livestock herders are at risk of collapse, with the wheat harvest delayed by a shortage of diesel fuel.
"The overall situation is characterised by severe insecurity and ongoing fighting which means that UN agencies do not have access to many areas," Jens Laerke, spokesman for the UN Office for the Coordination of Humanitarian Affairs (OCHA), told a news briefing in Geneva.
Many of the 200,000 residents of Douma, 15 km north of the capital, have fled to central Damascus, OCHA said.
Activists said on Wednesday that residents in the "ghost city" recovered mutilated corpses after a rampage by gunmen loyal to Assad and army shelling.
About 30,000 people have fled the eastern city of Deir al-Zor and moved north towards Hassaka and Al-Raqqa, OCHA said. Civilians are also leaving Hama, Idlib and Al-Raqqa and heading towards Aleppo.