Syrian opposition leaders were meeting in Turkey on Friday in a bid to settle their differences and forge a united front to confront the escalating conflict in their homeland.

"We will work towards a unified vision," said Burhan Ghalioun, who stepped down last month as head of the main opposition group the Syrian National Council in the face of mounting splits that were undermining its credibility.

The Istanbul meeting groups almost all opposition factions, while representatives from several Arab and Western countries were also present as observers, along with a representative of international Syria envoy Kofi Annan.

"We're here to define a common position," said Bassma Qodmani, SNC head of foreign relations. "There are not many more points of difference between us now."

The SNC has been criticised for failing to represent the array of ethnic and religious groups including Arabs, Kurds, Sunni Muslims, Alawites, Christians, Druze and others and for not touching base with the grassroots on the ground.

Last Sunday, the SNC appointed Kurdish activist Abdel Basset Sayda as its new leader who has pledged to embrace all groups to win a broader appeal.

Friday's only major absentee was the National Coordination Committee for Democratic Change, a large group of Arabs, Kurds and socialists, which said "technical problems" prevented them from attending, according to other participants.

But some factions remain suspicious about the prospect of change under the new leadership of the SNC, which is the main umbrella group opposing the regime of President Bashar al-Assad.

Activists had accused Ghalioun of ignoring the Local Coordination Committees, which spearhead anti-government protests on the ground in Syria, and of giving the Muslim Brotherhood too big a role.

UN officials have said Syria is now embroiled in full-scale civil war with activists saying more than 14,400 people have been killed since anti-regime protests erupted in March 2011, prompting a bloody crackdown by Assad's forces.

"I am not optimistic about the result... The people are fighting Bashar al-Assad because they need a democratic country, freedom, not just to replace Assad with Ghalioun or Sayda," said Ammar Qurabi, head of the small National Movement for Change.

"The revolution deserves better than this opposition," Qarubi told reporters.

Among the international observers in Istanbul, France and the United States are represented by their ambassadors to Damascus, who were recalled in November in protest at the violence at the hands of the regime.

Britain, Germany, Italy, Saudi Arabia, Turkey, Qatar and the United Arab Emirates also sent senior diplomats.

Friday's meeting comes ahead of a planned major conference organised by opposition groups in Cairo under the auspices of the Arab League, at a date to be announced.