Syria's opposition outlined its vision for an era after President Bashar al-Assad on Sunday, rejecting "all forms of terrorism" and vowing to keep weapons out of the "wrong hands" in a nod to the demands of its Western backers.
After six hours of meetings in a palace on the shores of the Bosphorus in Istanbul, the declaration by the main opposition Syrian National Coalition was welcomed by allies including the United States and Britain.
U.S. Secretary of State John Kerry said Washington would double its non-lethal aid to opposition forces in Syria to $250 million and that foreign backers had agreed to channel all future assistance through the rebels' Supreme Military Council.
Speaking after the "Friends of Syria" meeting of the opposition and their international backers, Kerry stopped short of a U.S. pledge to supply weapons that the anti-Assad insurgents have sought.
But he said the rebels' foreign backers were committed to continuing support to them and "there would have to be further announcements about the kind of support that that might be in the days ahead" if Syrian government forces failed to pursue a peaceful solution.
The pledge is far less than what is sought by U.S. allies Britain and France and some U.S. lawmakers.
British Foreign Secretary William Hague said the European Union would in the coming weeks discuss easing an arms embargo which has prevented weapons supplies to the Syrian rebels. His German counterpart, Guido Westerwelle, said Berlin was skeptical about arming the rebels but also said the EU must discuss it.
The opposition declaration vowed any weapons it attains would not fall into the wrong hands, a key concern of its Western backers, and said its goal was a "democratic, pluralistic" Syria.
Syria's al-Nusra Front, one of the most effective rebel forces battling Assad's troops, formally pledged allegiance to al Qaeda leader Ayman al-Zawahri this month. The United States has designated the Nusra Front a terrorist organization.
"We realize that there are radical and extremist elements in Syria which follow an agenda of their own. We firmly reject and condemn all forms of terrorism and any extremist ideology or mentality, as do the Syrian people," it said.
The coalition pledged it would not allow acts of revenge against any group in Syria, saying that members of Assad's administration "with blood on their hands" would be held accountable through fair trials.
'CLEAREST LANGUAGE YET'
The Syrian conflict began more than two years ago as peaceful demonstrations against Assad's rule but gradually became militarized under a heavy crackdown by his forces.
A subsequent civil war pitted the Sunni majority against members of Assad's Alawite sect, an offshoot of Shi'ite Islam, in a conflict which has killed more than 70,000 people.
"Today, it's safe to say that we are really at a critical moment," Kerry said. "The stakes in Syria couldn't be more clear: Chemical weapons, the slaughter of people by ballistic missiles and other weapons of huge destruction."
The Syrian opposition's Western backers have been alarmed at the rise of radical Islamist groups like the al-Nusra Front in the insurgent ranks, who consider Alawites and Shi'ites as infidels.
"We will not tolerate or allow acts of revenge and retribution against any group in Syria," the opposition coalition said in its declaration.
Britain's Hague said the declaration was "the clearest language" yet from the opposition in renouncing radical groups and committing to a democratic solution.
The crisis in Syria has divided world powers, with the United States, Europe, Gulf states and Turkey backing the opposition, while Russia, Iran and others have backed Assad.
Opposition leader Moaz Alkhatib urged Russia to play a positive role "to stop the bloodshed" in an increasingly sectarian war that risks engulfing the region.
"We strongly call on Iran not to get involved more than it has and to pull out its officers," Alkhatib told a joint news conference with Kerry and Turkish Foreign Minister Ahmet Davutoglu.
"(Iran) also has to ask Hezbollah to pull out its fighters from Syria in order to avoid dragging the region to a bigger battle," he said.
The rebels accuse the Lebanese Shi'ite movement Hezbollah of sending fighters to support Assad's forces. Several members of Hezbollah have been killed in clashes in villages near the Syria-Lebanon border.
The Syrian opposition had hoped the Istanbul meeting would give teeth to a tacit agreement that arming rebel groups is the best way to end Assad's rule.