The cease-fire, which includes Jaish Al-Islam, Jaish Ababil and Aknaf Beit Al-Maqdis, went into effect at midday Thursday.
“We announced a preliminary agreement over the will to enter into a cease-fire and de-escalation deal for the area,” said Jaish Al-Islam political leader Mohammed Alloush, adding that details will be worked out in the near future.
The announcement did not name the areas included, and did not mention the Syrian government. There was no immediate comment from Damascus.
Following a meeting with rebel factions, Alloush thanked Egyptian President Abdel Fattah El-Sisi for his role in the negotiations, and for pushing for a political solution to Syria’s war, Egypt’s Al-Ahram newspaper reported.
Backed by Russia, Iran and Shiite militias, the Syrian government has pushed back rebels across the country over the past year, shoring up its rule over the main urban centers.
A string of cease-fire deals in recent months has eased fighting in western Syria, including a truce in the southwest brokered by Russia and the US.
In recent months, Egypt has held negotiations with several Syrian opposition factions while maintaining good ties with Damascus.
Cairo mediated a cease-fire agreement in August in Eastern Ghouta after hosting talks between Syrian opposition factions and Russia’s Defense Ministry.
“Egypt is placing itself as an impartial meditator in the Syria crisis, and this is being welcomed by regional and international sides of the conflict, except for Turkey,” Egyptian political analyst Sameh Rashed told Arab News.
“Egypt began playing a mediator role in recent months, as the ongoing situation is pushing all sides of the conflict to seek a political solution instead of a military victory.”
Cairo will be in charge of monitoring parties’ commitment to the agreement, Rashed said.
Rebel factions hold a small pocket of territory south of Damascus, bordered to the west by a Daesh enclave and surrounded from the other sides by Syrian government troops and allied forces.
Through a series of military offensives and evacuation deals, the government has cleared out several opposition pockets around the capital.
Thousands of rebels and civilians have poured into rebel-held Idlib province in northwest Syria, transferred out of areas captured by government forces.