Fleeing residents say Boko Haram fighters are patrolling 50 kilometers (32 miles) of the main road between two of several towns the Islamic extremists have seized in a 200-mile (320-kilometer) arc running alongside northeast Nigeria's border with Cameroon.

A long-silent spokesman of Boko Haram called reporters to say fighters have seized the village of Mararaban Mubi, just outside Mubi town in Adamawa state. Mubi became a center for refugees who fled fighting in the past year. Spokesman Abu Zinnira also denied military claims that soldiers have retaken the city of Bama, 75 kilometers (45 miles) from Maiduguri, birthplace of Boko Haram and capital of Borno state.

The United States said it is launching a major border security program for Nigeria and its neighbors. Fighting recently spilled over into Cameroon.