"Armed bandits" have killed a Niger soldier and seriously wounded three others in Nigeria's volatile north-east, a high-ranking Niger security official told AFP Thursday, in new violence to hit an area considered as the homebase of Islamist sect Boko Haram.

"A soldier from Niger was killed yesterday (Wednesday) around 7:00 pm (1800 GMT) and three others were wounded in an attack by eight armed bandits on Nigerian territory," the official said on condition of anonymity.

The soldiers were part of a west African force based in Baga, a town located in Nigeria's restive northeastern state of Borno.

The three wounded soldiers were taken to a hospital in eastern Niger's Diffa, near the border with Nigeria.

Diffa-based private radio station Anfani claimed the soldiers were "ambushed by Boko Haram 10 kilometres (six miles) from the border with Niger".

Boko Haram has said it is fighting to create an Islamic state in Nigeria's mainly Muslim north, but the group is believed to be made up of different factions with varying aims.

The group has attacked churches, mosques, newspaper offices, the security forces, politicians and a UN building, among other targets.

According to an estimate earlier this year, Boko Haram's insurgency has claimed more than 3,600 lives, including deaths caused by the security forces. The current toll is likely much higher.