Nigeria’s police have offered a $300,000 (£177,000) reward to anyone who can help locate and rescue more than 200 abducted schoolgirls.

They were kidnapped more than three weeks ago by Islamist Boko Haram militants from their boarding school in the north-eastern state of Borno.

Eleven other girls were taken on Sunday night after two villages were attacked.

Another militant raid on a town near Cameroon killed some 300 people on Monday, a senator has revealed

Ahmed Zanna said the gunmen arrived in a convoy of vans in Gamboru Ngala during the town’s busy market day.

They stole food and motorbikes, burned hundreds of cars and buildings during their rampage

It is the latest attack to be blamed on Boko Haram, whose leader admitted earlier this week that his fighters had abducted the girls in the middle of the night from their school in the town of Chibok on 14 April.