The UN envoy on Syria Lakhdar Brahimi will meet senior US and Russian officials on Thursday, a day earlier than planned – in a bid to give impetus to a process he has described as laborious.
In Geneva, the Syrian government delegation says it is willing to discuss an opposition proposal to evict foreign fighters from the country.
The plan also calls for a transitional governing body to oversee a total ceasefire under UN monitoring.
The UN’s operation to bring aid to Homs and evacuate civilians has restarted after a temporary halt.
The city’s governor Talal al-Barazi told Reuters a humanitarian ceasefire could be extended to allow more people to leave the besieged old city – many of them visibly nervous after UN convoys came under fire last weekend.
Nearly half the city’s 2,500 civilians are thought to have been brought out.
The evacuees still include many men. Dozens have been detained by Syrian forces, suspected of being rebel fighters.
The governor said more than 100 had been released and nearly 200 were still being held in “good conditions”.
But fears remain for their safety. The UN has warned they must not come to harm. Britain’s Foreign Secretary William Hague has evoked the spectre of Srebrenica during the Bosnian war when thousands of men and boys were massacred after being separated from women and children.
The Homs operation remains delicate. Western nations say it is a drop in the ocean compared to humanitarian needs across Syria.