UN mediator Lakhdar Brahimi meets Syria's warring sides behind closed doors Thursday to gauge if they are willing to sit down face-to-face after the first day of a peace conference ended in bitter exchanges.

Brahimi will hold separate meetings with delegations from President Bashar al-Assad's regime and the opposition before full talks resume in Geneva on Friday.

The UN-sponsored conference - the biggest diplomatic effort yet to resolve Syria's devastating civil war - opened in the Swiss town of Montreux on Wednesday with heated disagreements among the two sides and world powers.

But neither side walked out and Brahimi said he would talk with both parties on Thursday to see "how best we can move forward."

Officials have said the talks could last between seven to 10 days and possibly resume after a break.

Expectations are very low for a breakthrough at the conference, but diplomats believe that simply bringing the two sides together for the first time is a mark of some progress and could be an important first step.

With no one appearing ready for serious concessions, mediators will be looking for short-term deals to keep the process moving forward, including on localized cease-fires, freer humanitarian access and prisoner exchanges. Brahimi said he "had indications" from both sides that they were willing to discuss these issues.

Hadi Al-Bahra, a member of the opposition National Coalition's delegation, said they would be meeting with Brahimi in Geneva to work out the details of Friday's talks.

Bahra told AFP the opposition was feeling confident after the regime adopted an aggressive tone for the start of the conference.

"What happened yesterday was clearly in our interest. We have heard very positive feedback from inside Syria and it is the first time we've felt so much support from Syrians for the Coalition," Bahra said.

In Davos on Thursday, Iranian President Hassan Rouhani said elections would be the best way to end Syria's civil war.

"The best solution is to organize free and fair elections inside Syria," Rouhani told the World Economic Forum. "No outside party or power should decide for the Syrian people and Syria as a country."

Syria's civil war has claimed over 130,000 lives and forced millions from the homes.

Al Qaeda chief Ayman al-Zawahiri late Wednesday called for the clashes to stop, urging in an audio message posted on the Internet for "every free person in Syria seeking to overthrow Assad ... to seek an end to fighting between brothers in jihad and Islam immediately."

AFP