Hundreds of Nigerian refugees returned home from Cameroon on Monday, seven years after they were displaced by Boko Haram jihadists and forced to seek shelter across the border, the UN said. 

Xavier Bourgois, spokesman of the UN High Commissioner for Refugees in Cameroon, said the returnees comprised "100 families, that is to say 342 people".

Speaking to AFP by telephone, he said they would be resettled "by the authorities inside the town of Banki where housing is being prepared for them."

But two militia sources gave a different figure, saying a total of 525 people, mostly women and children, were repatriated, crossing the border aboard buses and trucks.

Anti-jihadist militia leader Modu Gana told AFP by phone from Banki that Cameroonian officials had handed over the returnees -- all Banki residents -- to Babagana Umara Zulum, the  governor of Nigeria's northeastern Borno state, in the Cameroonian border town of Amchide.

The returnees were among some 100,000 Nigerians who had fled across the border into Cameroon since 2014 following deadly raids by Boko Haram jihadists.

Last month, Nigerian and Cameroonian officials met in the Cameroonian town of Maroua and agreed to the repatriation of 5,096 Nigerian refugees who were willing to return home, but the operation was postponed by a week.

"The first batch of the returnees... will be temporarily housed in shops in the local market," said Kyari Abdiye, member of another militia involved in resettling the refugees.

They will be screened for suspected jihadists "before they are allowed to move into their homes they deserted in 2014," he said.

Banki, 130 kilometres (80 miles) southeast of the Borno state capital Maiduguri, houses some 45,000 people displaced by the jihadist conflict in a sprawling camp.

Boko Haram has launched several attacks in and around Banki, targeting both troops and the displaced. 

The jihadist conflict, which has raged for more than a decade, has killed 36,000 people and displaced around two million from their homes in the northeast, according to the UN.

The violence has spread to neighbouring Niger, Chad and Cameroon, prompting a regional military coalition to fight the insurgents.