The main rebel group in the southern pocket of Syria's opposition-held eastern Ghouta told Reuters on Sunday it was negotiating with a United Nations delegation about a ceasefire, aid and the evacuation of urgent medical cases.
"We are engaged in arranging serious negotiations to guarantee the safety and protection of civilians," said Wael Alwan, the Istanbul-based spokesman for Failaq al-Rahman, in a voice recording.
"The most important points under negotiation are a ceasefire, ensuring aid for civilians and the exit of medical cases and injured people needing treatment outside Ghouta."
Alwan said the subject of "exit and evacuation" was "not on the table".
In a month-long assault, pro-Syrian government forces have marched into much of eastern Ghouta, the last major insurgent bastion around Damascus.
Troops have splintered Ghouta into three besieged zones in one of the bloodiest offensives of the seven-year war.
A number of patients requiring urgent medical attention have been evacuated from the northern pocket and some aid has entered there. This has not yet happened in the southern pocket.
The U.N. office for the coordination of humanitarian affairs (OCHA) said in a statement on Thursday at least 20,000 people have left eastern Ghouta in the past week, the majority of which came from the southern pocket through the Hammouriyeh area.
The Syrian army opened a corridor near Hammouriyeh this week and civilians have been making their way out towards army positions on foot, hauling their belongings with them.
OCHA said conditions for those remaining in eastern Ghouta are "dire".
"There is limited food, with reports of the usual ration of bread for one day being consumed over the period of a week to 10 days; insufficient sanitation and hygiene support for thoseliving in basements, and increased risk of communicable disease," it said.