Islamic State has claimed its first major attack since its "caliphate" was defeated at the weekend, after gunning down seven Western-backed fighters at a checkpoint in northern Syria.

Islamic State of Iraq and the Levant (Isil) militants opened fire on Syrian Democratic Forces fighters manning a checkpoint at the entrance to the city of Manbij, in what an SDF official called a “revenge attack”.

Isil claimed responsibility for the shooting, which occurred just after midnight on Tuesday morning, on their official news channel.

After a months-long battle further south in the village of Baghuz, SDF declared victory over the jihadists on Saturday.