Syrian opposition members face their final day of talks in Istanbul having set out 'preconditions' on entering international peace talks scheduled for next month in Geneva.
The Syrian National Coalition, so far deeply divided on how to take the movement forward, will meet for a final day in Istanbul on Thursday.
On Wednesday, they laid out what are being called preconditions for attending a proposed international meeting on Syria, spearheaded by the US and Russia, and which aims to bring the Syrian government and opposition together for the first time.
They want, among other requirements, Syrian President Bashar al-Assad to quit before they enter international peace talks.
"The participation of the Syrians in any conference is tied to the presentation of a deadline for a solution and giving the necessary binding international guarantees," said a statement released by the coalition.
"The Syrian Coalition welcomes the international efforts to find a political solution to what Syria has been suffering for two years while being committed to the principles of the revolution."
"The opposition wants to see guarantees by the international community - binding measures as they say in their own words - that Assad will not be part of any settlement agreement," said Al Jazeera's Rawya Rageh, reporting from Istanbul.
Several foreign envoys from different countries, including Saudi Arabia, had joined Wednesday's meeting.
Turkish Foreign Minister Ahmet Davutoglu participated in the meeting in what was seen as an effort to break the deadlock in talks to push the movement forward.
US ambassador to Syria Robert Ford and a top French diplomat on Syria also attended.
Veteran Syrian dissident Michel Kilo, head of a liberal bloc, also attended at the Istanbul hotel alongside a top Saudi official.
Our correspondent said: "It's very interesting that Kilo, a secular opposition figure whose internationally-backed bloc has been at the heart of the stalemate, arrived with these foreign officials and diplomats."
Saudi Arabia wants the Coalition to expand in order to water down the influence of the powerful Muslim Brotherhood, and has backed Kilo's bid to join the opposition group.
Opponents, including the Muslim Brotherhood, have resisted the Saudis' move.
Saudi Arabia, Qatar, France, Turkey and the United States all back the revolt against Syrian President Bashar al-Assad, but have conflicting visions for the National Coalition.
"Things are not moving. The opposition has hit its worst crisis yet," said a Coalition member on Wednesday, speaking on condition of anonymity.
The meeting is supposed to choose a new coalition president, agree on an interim government and vote in new members to join the bloc, as well as reach a decision on the proposed Geneva conference.
Meanwhile, Foreign Minister Walid Muallem told the Beirut-based Arab news channel Mayadeen that the Syrian government would allow its people to vote on agreements made at the so called Geneva 2 meeting.
"If we reach an agreement in Geneva, and I hope we will, it will be put to a referendum and if the people approve what we agreed upon, I can assure you it will be fully respected," Foreign Minister Walid Muallem said.
Muallem has already said earlier this month that the Syrian government will, in principle, send delegates to the Geneva 2 conference.
Also on Wednesday, the US, Turkey and Qatar pushed through a UN resolution demanding a probe into the fighting around the Syrian town of Qusayr, near Lebanon, and condemnation of foreign fighters supporting President Assad.
The resolution approved by a vote of 36-1 in the UN Human Rights Council calls for urgent investigation into alleged abuses by government forces and Hezbollah fighters in Qusair, along with more aid access and civilian protections.
Only Venezuela voted against it. Eight other nations in the 47-nation council abstained; two were absent.