The governor of the southern Diffa region in Niger has ordered residents of inhabited islands on Lake Chad to evacuate to the mainland by Monday because of the Boko Haram threat.

Niger's government said a Boko Haram attack on Karamga island in Lake Chad last weekend resulted in the deaths of 156 militants, 46 soldiers from Niger and 28 civilians.

A government official said Friday the military wants to launch an offensive to flush the Nigerian Islamic militants from hiding spots on the islands.

Gov. Yacoubou Soumana Gaoh said Thursday the military would help the fisherman, herders and farmers living on several islands move to the mainland under protection.

Lake Chad sits between Niger, Nigeria, Chad and Cameroon.