The armies of Niger and Chad have launched a major ground and air offensive against Boko Haram militants in northeastern Nigeria, a source from the Niger government says.

The offensive opened up a new front against the extremist Islamist group as part of regional efforts to combat them.

“Very early this morning, the troops from Niger and Chad began an offensive against Boko Haram… in the area of Bosso and near to Diffa,” the source said on Sunday.

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A resident of Diffa, located in Niger near the Nigerian border, said he saw troops headed toward the frontier early on Sunday followed by the sounds of heavy arms fire.

“After some time, the detonations grew further away, an apparent sign that the troops were moving inside Nigeria,” he said.

Privately owned radio station Anfani, based in Diffa, reported more than 200 vehicles, including those equipped with machine guns as well as tanks, ambulances, water tankers and transport trucks, in a convoy moving toward the Nigerian border.

It also reported that aircraft had targeted Boko Haram positions on Saturday and early on Sunday.

An aid worker said heavy arms fire was coming from the direction of the Doutchi bridge connecting Niger to Nigeria on Sunday morning.

On Friday, the African Union endorsed the creation of a regional force of up to 10,000 soldiers to join the fight against Boko Haram.

The force, the idea for which was adopted at an AU summit in January, will be based in Chad’s capital N’Djamena, the pan-African bloc’s Peace and Security Council said.

It will be mandated “to prevent the spread of Boko Haram activities and other terrorist groups” and “eradicate their presence,” the body agreed.

Diplomats said Chad, Nigeria, Cameroon, Niger and Benin had committed to providing troops, who would “operate freely” in a still-undefined region.