Speaking in the Hausa language, one of the masked militants who was brandishing a knife said it was to avenge the killing of the group's leaders in the Middle East earlier this year.

The BBC has not been able to verify the contents of the video or where the footage was shot.

It was published on an IS-linked news outlet and shows three groups of captives in civilian clothes.

The authorities have not yet commented on the video.

The IS militants, which operate in the Lake Chad region under the name Islamic State West Africa Province (Iswap), along with another Islamist militant group, Boko Haram, have recently suffered huge losses as a result of attacks by a multi-national military force.

Such military campaigns in the past have usually been followed by propaganda videos from the extremist groups.