The United States called on Wednesday for an overhaul of Syria's opposition leadership, saying it was time to move beyond the Syrian National Council and bring in those "in the front lines fighting and dying".
Secretary of State Hillary Clinton, signalling a more active stance by Washington in attempts to form a credible political opposition to Syrian President Bashar al-Assad, said a meeting next week in Qatar would be an opportunity to broaden the coalition against him.
"This cannot be an opposition represented by people who have many good attributes but who, in many instances, have not been inside Syria for 20, 30, 40 years," she said during a visit to Croatia.
"There has to be a representation of those who are in the front lines fighting and dying today to obtain their freedom."
Ms. Clinton's comments represented a clear break with the Syrian National Council (SNC), a largely foreign-based group which has been among the most vocal proponents of international intervention in the Syrian conflict.
U.S. officials have privately expressed frustration with the SNC's inability to come together with a coherent plan and with its lack of traction with the disparate internal groups which have waged the 19-month uprising against Assad's government.
Senior members of the SNC, Free Syrian Army (FSA) and other rebel groups ended a meeting in Turkey on Wednesday and pledged to unite behind a transitional government in coming months.
"It's been our divisions that have allowed the Assad forces to reach this point," Ammar al-Wawi, a rebel commander, told Reuters after the talks outside Istanbul.
"We are united on toppling Assad. Everyone, including all the rebels, will gather under the transitional government."
Ms. Clinton said it was important that the next rulers of Syria were both inclusive and committed to rejecting extremism.
"There needs to be an opposition that can speak to every segment and every geographic part of Syria. And we also need an opposition that will be on record strongly resisting the efforts by extremists to hijack the Syrian revolution," she said.
Syria's revolt has killed an estimated 32,000.
The meeting next week in Qatar's capital Doha represents a chance to forge a new leadership, Ms. Clinton said, adding the United States had helped to "smuggle out" representatives of internal Syrian opposition groups to a meeting in New York last month to argue their case for inclusion.
"We have recommended names and organizations that we believe should be included in any leadership structure," she told a news conference.
"We've made it clear that the SNC can no longer be viewed as the visible leader of the opposition. They can be part of a larger opposition, but that opposition must include people from inside Syria and others who have a legitimate voice which must be heard."
The United States and its allies have struggled for months to craft a credible opposition coalition.