Syria's fractious opposition, under pressure from the US and Qatar to unite, looked likely on Friday to agree to form an inclusive new opposition body that would serve as a unity government if Bashar al-Assad falls.

Qatar, which has bankrolled the opposition to Assad and played a leading role in Arab diplomacy against him, is hosting an opposition meeting, with senior US diplomats hovering on the sidelines, prodding the opposition to make a deal.

Rebel advances on the ground and increasing economic and social disintegration within Syria have added to the pressure on the opposition to form a body that can rule after Assad.

A source inside meetings that lasted into the early hours of Friday morning said members of the Syrian National Council (SNC), a group made up mainly of exiled politicians, had shifted views and were coming to accept the need to form a wider body.

"We will not leave today without an agreement," the source said.

"The body will be the sole legitimate representative of the Syrian people. Once they get international recognition, there will be a fund for military support."

The new body would mirror the Transitional National Council (TNC) that united the opposition to Muammar Gaddafi in Libya last year and then took power after he was ousted, the source suggested.

"They will create a 'temporary government', which could take control of embassies around the world and take Syria's seat at the UN, because the regime would have lost its legitimacy."

An outline agreement could see the SNC and other opposition figures agree on a 60-member political assembly, or congress, as well as a military and a judicial council.

The SNC, which has previously been the main opposition group on the international stage, may have around a third of the seats in the new body but would otherwise lose much of its influence.

Though it was not yet clear whether the groups meeting in Doha will name members to the new body or broach the thorny issue of its leadership, its creation would mark an advance long sought by the US and Qatar.

Separately, according to the United Nations refugee agency, around 9,000 Syrian refugees fled into Turkey in the past 24 hours

The latest exodus into Turkey (9,000), Lebanon (1,000) and Jordan (1,000) brings to 408,000 the total number of Syrian refugees registered or being assisted in the region, Panos Moumtzis of the UN High Commissioner for Refugees said Friday.

"It just indicates a significant crisis, the continuation of the conflict," Moumtzis told a news briefing in Geneva after aid agencies held a Syria humanitarian forum.

"In Turkey, we know from most refugees that they come from Aleppo or Idlib or northern areas. That has been the trend so far."