DOHA: The opposition Syrian National Council (SNC) begins a four-day meeting Sunday in Doha, where the United States will reportedly press for an overhaul of the coalition aiming to topple President Bashar al-Assad.

Details have emerged of plans to reshape the opposition into a representative government-in-exile, after US Secretary of State Hillary Clinton charged that the SNC was not representative.

Rebel forces in Syria have criticised the SNC as out of touch, and the opposition is also split ideologically.

The Doha talks come a day after rebels in northern Syria launched an offensive to take control of a key airbase.

Washington is pressing for a makeover of the opposition, with long-time dissident Riad Seif reportedly touted as the potential head of a new government-in-exile dubbed the Syrian National Initiative.Seif and about two dozen other leading opposition fiures gathered in Amman on Thursday and came up with proposals for a new body to represent the disparate groups opposing Assad.

Among those in attendance were some SNC members, former premier Riad Hijab, who defected in August; Ali Sadreddin Bayanuni of the Muslim Brotherhood and Kurdish and tribal representatives, participants said.

Participants sought to quell concerns the overhaul is aimed at building an opposition that would be willing to negotiate with Assad.

“Assad and his entourage leaving power is a non-negotiable precondition for any dialogue aimed at finding a non-military solution, if that is still possible,” they said in a statement.

The Amman meeting also supported “efforts underway to put in place a unified political body for the whole of the opposition,” according to the statement.

Hijab's spokesman, Mohammed al-Otri, said the group was proposing “the creation of a new political organ of the opposition, representing all of its components.”He said the new body would include the 14 members of the SNC executive, three members of the Kurdish National Council, representatives of on-the-ground activists and fighters, longstanding dissidents and religious leaders.

“It remains to be decided whether this body will replace the SNC or will constitute a new coalition,” Otri said, adding that the creation of the group “will certainly lead to the formation of a government” in exile.

In a separate statement, Bayanuni underlined the Brotherhood's support for “the idea of a political leadership to bring together the opposition” including the SNC.

But he said the Brotherhood supported maintaining the SNC, in which it holds significant influence, and “not replacing it with a new body.”The SNC lashed out on Friday at alleged US interference with the opposition, accusing Washington of undermining the revolt and “sowing the seeds of division” by seeking the overhaul.

Clinton has voiced frustration with the SNC, saying the exiled group was not representative of on-the-ground opposition forces and that it “can no longer be viewed as the visible leader of the opposition.”Washington later denied it was trying to dictate to the opposition, insisting it was simply seeking to ensure that more voices were heard.

While rebel fighters have been on the offensive on the ground, especially in northern Syria, the SNC has been on the defensive over a video posted on the Internet that appears to show opposition fighters beating and executing soldiers.

The SNC called for those responsible to be held accountable.

The meeting in Qatar, a key backer of the revolt in Syria, was originally due to take place on October 17 but postponed because of what an SNC official said was a flood of requests to join the group.

However, other SNC sources said the delay reflected deep internal tensions.

The SNC has emerged as the interlocutor of the international community since its creation around six months after the March 2011 start of the uprising which monitors say has cost more than 36,000 lives.

But divisions have dogged opposition ranks. Some groups -- unlike the SNC -- staunchly oppose foreign intervention and violent regime change.