Tense negotiations between the Syrian government and opposition focused on the transfer of power and helping besieged parts of the central city of Homs as they entered their fifth day.
There has been little progress so far toward resolving a key stumbling block over whether president Bashar Assad should step aside and transfer power to a transitional government.
Anas al-Abdeh, a member of the opposition Syrian National Coalition's negotiating team, said the transition specified in the June 2012 accord from the first round of Geneva peace talks remains "our main priority at the moment."
But he said negotiators would also raise the issue of bringing humanitarian aid convoys to Homs, adding "the regime is still insisting on its systematic starvation policy."
The focus on Homs and release of detainees are meant as confidence-building measures. A tentative agreement was reached in Geneva at the weekend for the evacuation of women and children trapped in Homs before aid convoys go in. Central Homs has been under siege for nearly two years.
In a statement Talal Barrazi, governor of the Homs province, said police, paramedics and the Syrian Arab Red Crescent were ready to arrange the evacuation and "we are waiting for the UN's response." But UN-Arab League mediator Lakhdar Brahimi said security problems were delaying the evacuation.
A spokeswoman for the World Food Programme said trucks were on standby to deliver food and help those who choose to be evacuated, but added, "We need that all security conditions be met to allow this inter-agency convoy to go,"
"This convoy cannot be a fig leaf only. We need access to all parts of Syria, all parts of the people in need," she said.
A complication in getting aid to and evacuating people from Homs is that the negotiators have limited influence over the armed groups that have gained control as Syria's uprising since March 2011 slowly evolved in an insurgency.
Veteran UN mediator Lakhdar Brahimi said: "There are no miracles here," adding that both sides nevertheless appeared to have the will to continue the discussions.
Asked how he planned to bridge the enormous gap between the two sides, the diplomat quipped: "Ideas, I'll take them with great pleasure."