Suspected Boko Haram fighters have abducted dozens of boys and men in a raid on a remote village in northeast Nigeria, loading them onto trucks and driving them off, witnesses who fled the violence said.

Several witnesses who arrived as refugees in the city of Maiduguri told Reuters news agency on Friday that the fighters had also killed six older men in last Sunday's raid on the village of Doron Baga, in which several houses were burned.

As many as 97 people are unaccounted for, the villagers said.

The kidnappings come four months after Boko Haram, which is fighting to reinstate a medieval Islamic caliphate in religiously mixed Nigeria, abducted more than 200 schoolgirls from the village of Chibok.

"They left no men or boys in the place; only young children, girls and women," said Halima Adamu, sobbing softly and looking exhausted after a 180 km road trip on the back of a truck to the northern city of Maiduguri.

"They were shouting 'Allah Akbar' (God is greatest), shooting sporadically. There was confusion everywhere. They started parking our men and boys into their vehicles, threatening to shoot whoever disobey them. Everybody was scared."

Boko Haram, seen as the number one security threat to Africa's top economy and oil producer, has dramatically increased attacks on civilians in the past year, and the once-grassroots movement has rapidly lost popular support as it gets more blood thirsty.

Its solution - kidnapping boys and forcing them to fight and abducting girls as sex slaves - is chilling echo of Uganda's Lord's Resistance Army, which has operated in the same way in Uganda, South Sudan and central Africa for decades.

The military did not respond to a request for comment. A security source said they were aware of the incident but were still investigating the details.