The government of Niger says the army has killed more than 280 Boko Haram militants in days of land and air raids near the border with Nigeria.

In a statement read out on Niger state television, the defence ministry said most of the Islamist militants had died in air strikes.

The army said its troops had also captured rocket launchers, assault weapons and ammunition during an offensive on islands in Lake Chad and along the Komadougou Yobe river.

Niger has recently expressed concern about setbacks at the hands of Boko Haram suffered by Nigeria where the jihadists' insurgency began 10 years ago.