The Nigerian military has killed and wounded children in an airstrike in neighbouring Niger, a local governor in Niger, state television and an aid agency said on Sunday, although Nigeria's armed forces said they were still investigating.

The attack took place in the village of Nachadé in the region of Maradi, Niger, on Friday, a few kilometres from the border with Nigeria, said Chaibou Aboubacar, governor of Maradi. He said seven children were killed and five wounded.

He did not say how he knew that Nigerian forces carried out the attack. Niger's state television also said it was carried out by Nigerian forces, without providing evidence.

"As a matter of policy, the Nigerian Air Force does not make any incursions into areas outside Nigeria's territorial boundaries. That's our policy," Jimmy Akpor, Nigeria's Director of Defence Information, said. He said an investigation was underway.

Medical charity Medecins Sans Frontieres, which cared for some of the wounded, confirmed the strike. It said that 12 people died, including four children. Local inhabitants told MSF that Nigerian forces were pursuing targets who had fled a border town.

The specific reason for the strike was not clear. It occurred in a region where banditry is common and where both governments fear that Islamist insurgents linked to Islamic State are gaining ground.

Reuters