The Syrian Observatory for Human Rights said on Wednesday a local 15-day ceasefire between Syrian rebels and government forces in the Eastern Ghouta area near Damascus would be announced “in the coming hours”.
The ceasefire will take effect early on Thursday as a “test period” that could be extended if there is further agreement, the British-based Observatory said.
It gave no precise time for the start of the ceasefire, however, and said an agreement had yet to be finalised.
Clashes were ongoing between rebels and pro-government forces late on Wednesday, the Observatory said.
There was no immediate mention of the agreement on Syrian state media and a rebel leader was not immediately available for comment.
It would be the second local ceasefire to take effect in recent months.
Rebels and pro-government forces reached a deal in September to end hostilities around a town near the Lebanese border and two villages in the northwest for a period of six months.
That ceasefire, which was backed by Iran and Turkey in a rare success for foreign diplomacy, appears to be largely holding despite isolated incidents of firing by both sides.
But fighting still rages across much of the rest of Syria in a 4-1/2-year-old civil war that has killed 250,000 people.
Rebel-held Eastern Ghouta, which was targeted with chemical weapons in 2013, has come under intense bombardment from government warplanes in recent months.