The main rebel group in the southern pocket of Syria's opposition-held eastern Ghouta said on Sunday it was negotiating with a United Nations delegation about a cease-fire, 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.

"The most important points under negotiation are a cease-fire, ensuring aid for civilians and the exit of medical cases and injured people needing treatment outside Ghouta."