Syria Geneva II peace talks highlight gulf over Assad
The first day of a major Syrian peace conference in Switzerland has ended amid bitter divisions over the future of President Bashar al-Assad.
The US said Syria could not be saved while he was in power. Syria's team insisted: "President Assad is staying."
The talks now move to Geneva on Friday, with the UN saying it was hopeful of some movement on local ceasefires and access to humanitarian aid.
Syria's conflict has left more than 100,000 dead and millions displaced.
The first day of the conference was held in the Swiss city of Montreux.
At a fractious end-of-day news conference, during which there were repeated calls for calm, UN Secretary General Ban Ki-moon spoke of the suffering in Syria, saying: "Enough is enough. The time has come to negotiate."
He said that "the really hard work begins on Friday", adding: "We have a difficult road ahead, but it can be done and it must be done."
He added: "We did not expect instant breakthroughs. No-one underestimated the difficulties."
UN mediator Lakhdar Brahimi said he would speak to the Syrian government and main opposition delegations separately on Thursday and that he hoped both teams would meet in the same room on Friday.
He said: "We have had some fairly clear indications that the parties are willing to discuss issues of access to needy people, the liberation of prisoners and local ceasefires."
The BBC's Paul Wood in Montreux says that when the talks do go behind closed doors, it is hoped there will be a more constructive tone.
However, a huge gulf remains between the Syrian team and that of the opposition and its allies.
US Secretary of State John Kerry said: "There is no way - no way possible in the imagination - that the man who has led the brutal response to his own people could regain the legitimacy to govern.
"One man and those who have supported him can no longer hold an entire nation and a region hostage."
However, earlier in the day, Syrian Information Minister Omran al-Zoubi told reporters: "There will be no transfer of power and President Bashar Assad is staying."
Syria's UN ambassador Bashar Jaafari said the government was willing to discuss all aspects of Geneva communique, which lays out a political transition plan for Syria.
However, he questioned some parties over their "obsession that if they get rid of Bashar al-Assad things will be better in Syria".
Mr Jaafari pointed to developments in Libya and Iraq following the removals of Muammar Gaddafi and Saddam Hussein.
He also condemned many of Wednesday's speeches, by 40 or so foreign ministers, as "provocative and repetitive statements based on hatred towards the Syrian government".
The Syrians also expressed anger at the withdrawal of an invitation to the talks to its key ally, Iran.
Another key sticking point is the Geneva I communique, agreed at a previous summit, which calls for a transitional government in Syria with full executive powers and which forms the basis of this new round of talks.
Mr Kerry said: "Every delegation, with one exception, embraced the Geneva communique," referring to the Syrian government.
Mr Ban said he was disappointed with the attitudes of both the Syrian government and Iran.
Syria has indicated that ending what it calls "terrorism" must be a priority of the communique.
But the head of the main opposition National Coalition, Ahmad Jarba, said the Syrian government must sign up to a deal to transfer powers.
Mr Jarba said that this would be "the preamble to Bashar al-Assad's resignation and his trial alongside all the criminals of his regime".
His comments came during a bitter morning exchange during which Syria's Foreign Minister Walid Muallem said some of states attending the talks had "Syrian blood on their hands" and that the opposition were "traitors".
Russian Foreign Minister Sergei Lavrov sought to play down the differences.
He said: "As expected, the sides came up with rather emotional statements, they blamed one another."
But he added: "For the first time in three years of the bloody conflict, the sides - for all their accusations - agreed to sit down at the negotiating table."