The Syria peace talks reached a breakthrough today as the regime and opposition agreed the evacuation of women and children from the besieged city of Homs.
Negotiations made a tentative start yesterday as both sides talked separately to the UN mediator, Lakhdar Brahimi.
Mr Brahimi acknowledged that the Homs agreement fell short of his hope to send a humanitarian aid convoy, but he said: "to bring Syria out of the ditch in which it has fallen will take time."
A senior US official said the regime "is blocking all convoys to Homs, and has been doing so for months". He added: "The situation in Homs is extremely urgent. Anything the government says to the contrary is false."
Mr Brahimi also defended the pace of the talks, which have yet to touch upon the issue of President Assad's future. "I think being too slow is a better way than going too fast," he said. "If you run, you may gain one hour and lose one week."
The Syrian opposition has also agreed to a request by the government to provide lists of prisoners held by various armed groups.
ITV News Correspondent Neil Connery reports:
Mr Brahimi said that meeting delegates from both sides separate had been "very useful" to the peace talks, and expected the same to occur again tomorrow after the government and opposition sit together once more.
He said the thorniest topic - a possible transitional government - will not come up until at least tomorrow.
Foreign secretary William Hague said the UK government is "looking at" the option of allowing Syrian refugees to return home.
The opposition is seeking the release of about 50,000 detainees and has tried to focus efforts on humanitarian aid, although the government has said negotiations should focus on the broader crisis.
Today's morning session was intended to build trust between the two sides, who are at odds over the fate of President Bashar al-Assad.
Monzer Akbik, an opposition spokesman, said the coalition was still determined to stay for the political talks set to begin tomorrow. He accused the government of using "stalling techniques".