Syrian peace talks in Geneva were set to tackle the explosive issue of a transfer of power on Monday, despite President Bashar al-Assad's repeated vows that he will not step down.
After two days of talks focused on humanitarian issues, the UN-sponsored discussions between Syria's regime and opposition were to move on to the core issue of a transitional governing body.
The UN said in a terse statement that the talks had resumed around 11:00 am (1000 GMT) but provided no further details.
In the first tangible promise to emerge from the talks, UN mediator Lakhdar Brahimi said Sunday the regime had agreed to allow women and children safe passage from besieged rebel-held areas of the city of Homs.
But opposition spokesman Louay Safi said the time had come "to start talking about transition from dictatorship to democracy".
On Monday, he said, "we start to see if the regime is willing to go to a political solution or stick to a military one."
The opposition says Assad must leave power and a transitional government be formed based on an agreement reached during a first peace conference in Geneva in 2012.
The regime says Assad's role is not up for debate at this conference -- dubbed Geneva II -- and denies that the initial Geneva deal requires him to go.
In Damascus, official Syrian media made it clear that Assad's continued leadership remained a red line that negotiators would not cross.
"Those who are deluding themselves must understand that the government delegation to Geneva II did not go to this conference to hand power to those who have conspired against the people over the last three years," the Tishreen state newspaper said.
"They are in Geneva to speak in the name of the Syrian people who have been the target of terrorism by armed groups linked to Al-Qaeda," it said.
The regime accuses the opposition and its international backers of promoting "terrorism" in the country, pointing to militant Islamist rebel groups like the Islamic State of Iraq and the Levant (ISIL) and the Al-Nusra Front.
The pro-regime Al-Watan newspaper said any optimism about the talks had faded because of the opposition's "inability to negotiate" and warned: "The collapse of the negotiations is now possible."
Brought together by the United Nations, Russia and the United States, the two sides have been meeting in the biggest diplomatic push yet to stem Syria's bloodshed after nearly three years of civil war.
Erupting after the regime cracked down on protests inspired by the Arab Spring, the conflict has claimed more than 130,000 lives and forced millions from their homes.
Brahimi, who has been acting as a go-between for the two sides, has said he is "happy" with the mood and that the parties are acting with "mutual respect".
But he has admitted that progress has been difficult and the two sides are moving very slowly.
The regime's promise on Sunday to allow women and children to leave the besieged parts of Homs raised some hopes of humanitarian relief, but was greeted by scepticism on the ground.
Activists in rebel areas of Homs said residents had "no trust" in the regime and first wanted aid supplies and guarantees that those leaving would not be arrested.
The opposition also raised concerns about a regime demand to receive a list of names of men who want to leave, saying this was part of intelligence gathering.
The Old City of Homs has been under siege since June 2012 after rebels there rose against the regime, with an estimated 500 families living with near-daily shelling and the barest of supplies.
Brahimi repeated his hope on Sunday that a convoy of humanitarian aid could enter the besieged area on Monday, saying rebel forces had already agreed and the local governor was considering the issue.
Sunday's talks also touched on possible prisoner exchanges, with the opposition saying it had a preliminary list of 47,000 people held by the government, including 2,300 women and children whose names it had submitted.
Regime officials said it also wanted lists of prisoners in rebel hands, insisting that the issue be discussed "without discrimination". It also denied it was holding any children.
Pitting Assad's regime, dominated by the Alawite offshoot of Shiite Islam, against largely Sunni Muslim rebels, the war has unsettled large parts of the Middle East.