International mediator Lakhdar Brahimi, trying to halt the bloodshed in Syria, met senior US and Russian officials in Geneva on Friday, but prospects for a breakthrough were dim.
Mr Brahimi held separate talks with Russian deputy foreign minister Mikhail Bogdanov and US deputy secretary of state William Burns, whose governments back opposing sides in Syria's 21-month-old conflict, at the United Nations' European headquarters. All three then met together behind closed doors.
A US official said they would focus on "creating the conditions to advance a political solution - specifically a transitional governing body" agreed at Geneva talks in June.
That accord among world powers left open the fate of Syrian president Bashar al-Assad, facing rebels seeking to topple him in an armed struggle that has cost more than 60,000 lives. Mr Brahimi suggested this week that Assad should quit.
Syria denounced Mr Brahimi as "flagrantly biased" on Thursday, casting doubt on how long the UN-Arab League mediator can pursue his peace mission.
"The US position is clear: Assad has lost all legitimacy and must step aside to enable a political solution and a democratic transition that meets the aspirations of the Syrian people," the US official said, asking not to be named.
Before the meeting, Mr Bogdanov gave no indication Russia would abandon its insistence that Dr Assad must not be forced out by external powers and that his exit cannot be a precondition for a Syrian political dialogue.
Russia is "eagerly awaiting bringing the agreements reached in Geneva to life without damaging the sovereignty and territorial integrity of Syria and without violating the right of the Syrian people to choose their own leaders," Mr Bogdanov was quoted as telling Russia Today television.
A Geneva-based Arab diplomat said that he expected Moscow to bring some fresh ideas to the negotiating table. "The Russians asked for this meeting, so they must be coming with something," he said. "At the same time, they don't want to let Bashar go."
Winter weather is making life even harder for some two million displaced people in Syria and over 600,000 registered Syrian refugees in Lebanon, Turkey, Iraq, Jordan and Egypt.
"More than two million Syrian children affected by conflict, or in refugee camps in neighbouring countries are struggling to stay warm and dry as one of the harshest winters in recent years sets in," Marixie Mercado of the Unicef told a news briefing in Geneva.
Earlier, Minister for Foreign Affairs Eamon Gilmore called on the United Nations to use the powers of the International Criminal Court (ICC) to investigate the atrocities in Syria.
Ahead of the meeting in Geneva, Mr Gilmore said the ICC should be used to bring the perpetrators of violence to justice in the manner it was used in the Balkans conflict.
"All of the attempts that are being made to try and get a settlement to it, to try and get some type of a political process have not worked to date," said Mr Gilmore this morning.
"And those who are responsible for the slaughter, those who are carrying it out, and those who are directing it have to know that there will be a consequence, just as 20 years ago there was a consequence for those who slaughtered people in the Balkans.
Ireland is one of the joint signatures on a letter sent to the UN Security Council, along with Austria, Slovenia and Denmark, looking for the ICC to open an investigation.
Mr Gilmore told Morning Ireland that the letter was sent "so that an investigation can be conducted by the International Criminal Court, so that those that are involved in it know that at the end of the day when this conflict is over, as it will end at some stage, there will be a consequence and those that are responsible for slaughtering their fellow citizens will be brought to book and brought to account."