An officer and other witnesses say soldiers killed scores of Islamic extremists in a rare victory as the insurgents advanced on a town near the northeast Nigerian city of Maiduguri.

One officer said a feared Boko Haram commander was among some 200 militants killed in a battle Friday in Konduga town, 35 kilometers (22 miles) from Maiduguri, the capital of Borno state and birthplace of the extremist group. The officer spoke on condition of anonymity because he is not authorized to speak to reporters.

Boko Haram in recent weeks has taken a string of towns stretching over 200 miles (320 kilometers) alongside Nigeria's northeast border with Cameroon in a new campaign to create an Islamic caliphate.

The United States has said it is launching a major border security project for Nigeria.