Russian-sponsored talks are planned in Astana on Tuesday. The last round of Astana talks in May led to the signing of an agreement between Iran, Russia and Turkey to create four de-escalation zones in Syria, one of which is in the south.
But fighting has continued in frontline areas, including in Deraa city in southern Syria, with hostilities expanding to the border province of Quneitra along the Israeli-occupied Golan Heights.
A rebel official said the latest ceasefire was a ploy to drag the opposition to Astana. The rebel side has already expressed deep misgivings about the de-escalation zones, which they say benefit the Syrian army by freeing forces to allow them to make territorial gains elsewhere.
"This ceasefire is an attempt by the Russians and the regime to bring back the opposition to Astana and give them assurances on the ground they will stop the shelling on condition they attend," said Sohaib Alraheel, spokesman of Liwa al Fuqan, a faction of the rebel Free Syrian Army (FSA) operating in southwest Syria.
A spokesman for the Southern Front, a coalition of Western-backed FSA rebel groups, cast doubt on whether the Syrian government army and its Iranian-backed allies would halt attacks on the front lines in Deraa and in Quneitra province.
"The Free Syrian Army are very distrustful of the regime's intentions in abiding by the ceasefire. It will be like the previous one," Major Issam al Rayes told Reuters.