The US has launched strikes against militants linked to the Islamic State group (IS) in north-western Nigeria, where jihadists have long carried out an insurgency.

Camps run by the group in Sokoto state, which lies on Nigeria's border with Niger, were hit, the US military said, adding that an "initial assessment" suggested "multiple" fatalities.

US President Donald Trump said the strikes were "powerful and deadly" and labelled the group "terrorist scum", saying it had been "targeting and viciously killing, primarily, innocent Christians".

Nigerian Foreign Minister Yusuf Maitama Tuggar told the BBC it was a "joint operation" and had "nothing to do with a particular religion".