Chadian troops have rescued around 85 Nigerians kidnapped by Boko Haram Islamists last weekend from fishing communities in Nigeria’s extreme northeast, security and human rights sources said Saturday.

Nearly 100 young men and several women were snatched in a raid by insurgents late on Sunday and ferried across the border into Chad, witnesses said.

The raid on Doron Baga, a fishing village on the shores of Lake Chad, left 28 people dead and scores of homes burned, according to residents.

“We received communication from our Chadian counterparts of the interception of a convoy of buses carrying 85 Nigerians believed to have been kidnapped by Boko Haram terrorists from Baga,” a senior security official in Maiduguri told AFP.

“The convoy being led by six Boko Haram gunmen was stopped on the Chadian part of the border along Lake Chad for routine checks and the huge number of people in the convoy raised suspicion,” he said.

The suspects have given conflicting information on the hostages they were accompanying and their destination, added the source, who asked not to be named.

An official of the National Human Rights Commission (NHRC) in Maiduguri said 65 men and 22 women had been rescued in the operation, but said more than 30 are still suspected to be held by the extremists.

The militants sped off in motorboats when they sighted the convoy being interrogated by soldiers, said the official, on condition of anonymity.

The rescued villagers are being kept in custody by Chadian authorities, and it was not clear when they will be brought back to Nigeria.

Boko Haram, which wants to create an Islamic state in mainly Muslim northern Nigeria, has been accused of kidnapping hundreds of people in the northeast to use as conscripts, wives and slaves.

The April 14 abduction of the schoolgirls from the remote Borno town of Chibok drew unprecedented international attention to the conflict and offers of help from Western powers.

Forced conscription by Boko Haram is also becoming an increasing problem in neighbouring Cameroon, where authorities say hundreds of young men and boys have been press-ganged by militants near their strongholds in the north of the country.

More than 2,000 people have been killed and nearly 650,000 displaced this year by Boko Haram, the deadliest toll since its insurgency began in 2009.