Syrian state media said Sunday that air defences had opened fire near Damascus airport, before withdrawing the report after what appeared to be a false alarm.

Iran's Revolutionary Guards said Monday they launched a missile strike against a "terrorist" headquarters in Syria in retaliation for an attack that killed 24 people in the Iranian city of Ahvaz.

Disagreement between Turkey and Russia over how to tackle the Syrian rebel stronghold of Idlib seems to have deferred a looming regime offensive on the province, analysts say.

Russia and Turkey are on opposite sides of the conflict, but key global allies.

Russia on Saturday said Syrian rebels are preparing a chemical attack in Idlib province which will be blamed on Damascus and used as a pretext for Western powers to hit government targets in the war-torn country. 

Moscow's accusation comes after US President Donald Trump's national security adviser John Bolton this week said Washington will respond "very strongly" if Syrian President Bashar al-Assad uses chemical weapons in an offensive to retake Idlib, one of the last rebel held provinces in the country. 

The rebels in southern Syria targeted by a major government offensive were long supported by Washington and seen as symbolizing relatively moderate opposition to Damascus.

The U.N. struggled on Friday to get a new round of Syrian peace talks off the ground, but with few signs of progress as dozens more civilian deaths underlined the scale of the challenge.

A dozen Syrian rebel factions have suspended talks on new peace negotiations, accusing President Bashar Assad's regime of violating a four-day-old ceasefire with attacks near Damascus that continued Tuesday.

The decision threatens the process sponsored by regime ally Russia and rebel backer Turkey, which began with a truce and is meant to lead to negotiations in the Kazakh capital Astana this month.

The White Helmets, a Syrian civil organization of emergency responders in rebel-held areas, on Thursday won the Right Livelihood Award, the jury for the Swedish human rights prize announced.

A massive bomb blast claimed by the Islamic State group killed at least 44 people and wounded dozens on Wednesday in the Kurdish-majority Syrian city of Qamishli.

It was the largest and deadliest attack to hit the city since the beginning of Syria's conflict in March 2011.

Syrian government air strikes on rebel-held neighborhoods of divided second city Aleppo killed at least 15 civilians on Wednesday, a monitor said.

The Syrian Observatory for Human Rights said at least 10 of the dead came in raids just outside the Al-Bayan hospital in the Shaar neighborhood.