Three soldiers from Nigeria and Niger were killed and at least 12 others were injured on Sunday after attacks by Islamist fighters in northeastern Nigeria, two military sources said on Monday.

The troops were part of the Multinational Joint Task Force (MNJTF) made up of forces from Benin, Cameroon, Chad, Niger, and Nigeria that are seeking to end an Islamist insurgency that has killed thousands and displaced millions more.

A Nigerian military source said that two Nigerian soldiers of the MNJTF were killed when their vehicle set off an improvised explosive device while they were pursuing insurgents in the Arege area in northeastern Borno state, the heartland of the insurgency.

Ten troops, including the commanding officer, were injured and another two civilians working with the troops were also wounded, the source added.

A Nigerien soldier was killed when the vehicle he was travelling in detonated another explosive device in a separate part of Arege, while the number of wounded was not immediately known, a source with the Nigerien army said.

An MNJTF situation report seen by Reuters confirmed the attacks.

MNJTF spokesman Lieutenant Colonel Kamarudeen Adegoke was not reachable for comment.