At least 20 people, most of them rebel fighters, have been killed and dozens injured in a bombing near Syria’s border with Turkey, activists say.

The attack reportedly occurred during a change of guard at the rebel-controlled Atmeh crossing, in Idlib province.

It was not immediately clear whether the blast was caused by a suicide bomber or a remote-controlled device.

But a news agency linked to so-called Islamic State (IS) said a suicide car bombing had targeted a rebel convoy.

Photographs and video footage purportedly of the aftermath of the attack showed the bloodied bodies of more than 20 men, some of them wearing camouflage trousers.

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Rebel fighters have been targeted by the jihadist group at the Atmeh crossing before. In mid-August, 32 were killed in a suicide attack claimed by IS.

A Turkish-backed rebel force is also currently battling IS militants in another border region, about 60km (37 miles) to the north-east.

The rebels – assisted by Turkish warplanes, tanks and special forces personnel – are approaching the outskirts of the IS stronghold of Dabiq, just over a month after sweeping into the town of Jarablus.

Dabiq holds great symbolic value to jihadists as it is named in Islamic apocalyptic prophecies as the site of a showdown between Muslims and their enemies.