Air strikes on a market killed at least 53 people, including children, in a town in northern Syria on Monday despite a "de-escalation zone" in place there, a monitor said.

The Britain-based Syrian Observatory for Human Rights said it was not immediately clear whether the strikes on rebel-held Atareb had been carried out by Syrian warplanes, or those of Damascus's ally Russia.

The monitor said three strikes hit the town's market, adding that five children were among the dead, as well as three policemen.

A photographer contributing to AFP saw massive destruction at the scene, with rubble from damaged buildings covering the street and panicked civilians carrying away the injured.

Three men helped one of those hit in the attack, his face drenched in blood and his features almost completely obscured.

Nearby, the body of a man in a blue shirt and dark trousers lay where he had died.

Civil defence workers rushed alongside civilians to evacuate the injured, with one man in a thick beanie hat carrying a wailing child in a pink sweater away from the scene.

Elsewhere, the bodies of at least three children were laid out on the ground, partly covered by thick bolts of fabric.

Atareb is in the west of Aleppo province, in an area that is part of a "de-escalation zone" agreed under a deal earlier this year between Syria's allies Russia and Iran, and rebel backer Turkey.

The zone mostly covers neighbouring Idlib province, which is largely held by opposition forces and a jihadist group formerly affiliated with Al-Qaeda.

Despite the government's recapture of Aleppo city late last year, rebel groups maintain a presence in the west of the province.

Russia, a key ally of Syria's President Bashar al-Assad, began a bombing campaign in support of his government in 2015.

Since then, with Moscow's support the government has recaptured large swathes of territory from opposition forces.

Moscow has steered the so-called Astana process that in May led to a deal to create four so-called "de-escalation zones" across Syria.

The zones have produced a drop in violence, but sporadic fighting and bombardment has continued, and promised humanitarian access has not materialised.

More than 330,000 people have been killed in Syria since the conflict began in March 2011 with anti-government protests.

Source: AFP