BAUCHI, Nigeria -- A fleeing survivor says Boko Haram extremists have burned down six northeast Nigerian villages and killed 37 people near the insurgents' Sambisa Forest stronghold.

Anti-Boko Haram youth vigilante Ahmed Ajimi says many victims of Wednesday night's attacks were farmers who had recently returned home after soldiers earlier this year forced the extremists out of the area where they had declared an Islamic caliphate.

Hit-and-run attacks and suicide bombings have continued. Boko Haram last week denied Nigerian military reports that militant fighters are hemmed into the Sambisa Forest and claimed its insurgents still hold towns hundreds of kilometres (miles) away. There was no way to verify the claims.

Ajimi said in a telephone call Friday that he hid in the bush and returned Thursday to help bury 37 bodies.