Forces from Niger and Chad have launched a ground and air offensive against militant group Boko Haram in north-eastern Nigeria, officials say.
The campaign is said to be targeting militants in Borno state.
It came as Nigerian officials dismissed Boko Haram’s pledge of allegiance to Islamic State as a reaction to military pressure from Nigeria and its allies.
The pledge was posted online on Saturday in an audio message by Boko Haram leader Abubakar Shekau.
He called on Muslims everywhere to swear loyalty to IS leader Abu Bakr al-Baghdadi.
Boko Haram has been fighting an insurgency to create an Islamic state in northern Nigeria since 2009, and in recent months the violence has increasingly spilled over into neighbouring states.