A Niger military official says seven soldiers were killed in an overnight attack by Boko Haram on the island of Karamga in Lake Chad, the body of water touching the four countries that have been targeted by the Nigeria-based insurgency.

Col. Salaou Barmou said 14 Boko Haram assailants were also killed in the fighting Friday night.

Karamga is about 100 kilometers (62 miles) from Diffa, the Niger border town that has come under repeated attack by Boko Haram recently.

Niger President Mahamadou Issoufou visited Diffa Saturday to deliver a message of support to the security forces, vowing that Boko Haram would be defeated.

After months of gains from Boko Haram, military forces from Nigeria and Chad have reported retaking at least a dozen towns in recent weeks.