Cameroonian officials say Boko Haram fighters who attacked a town in the far north killing nearly 100 people have retreated to Nigeria.

Government spokesman Issa Tchiroma Bakary said Friday that Cameroonian soldiers assisted by Chadian forces successfully chased hundreds of the Islamic extremists out of the town of Fotokol.

Boko Haram's assault inside Cameroon marked an escalation by the Nigerian-based militants who are blamed for killing more than 10,000 people last year.

After being bombed out of several Nigerian towns, hundreds of Boko Haram fighters responded by attacking Fotokol in Cameroon, razing mosques and churches and warning Nigeria's neighbors not to join the battle against their insurgency.

Last week, African leaders authorized a 7,500-strong force to fight the extremists, including pledges of troops from Nigeria, Cameroon, Chad, Niger and Benin.