More than 100 people are missing after jihadists in northeast Nigeria carried out a mass kidnapping that targeted women and children from displacement camps, officials told AFP on Thursday.

Anti-jihadist militia leaders have blamed Islamic State West Africa Province (ISWAP) for last week's attack in Borno state, the heart of a jihadist insurgency which has left more than 40,000 people dead and two million displaced since 2009.

Several details about the attack in rural Ngala are still unclear and officials have given conflicting accounts. The number of people reported missing does not necessarily reflect the number held in captivity.

The UN's Office for the Coordination of Humanitarian Affairs (OCHA) said the attack took place on Thursday last week and estimated over 200 people from camps for displaced people had been abducted.

It said armed attackers took the women while they were out collecting firewood.

"The United Nations strongly condemns the reported abduction of internally displaced persons (IDPs), many of them women, boys and girls," it said.

"The exact number of people abducted remains unknown but is estimated at over 200 people."

OCHA told AFP the figure came from initial estimates from community leaders, and said headcounts were being carried out in four displacement camps to verify the number.

It said the camps house almost 104,000 people, mostly women and children.

Ali Bukar, an officer at the Ngala Local Government Information Unit, told AFP families had confirmed 113 people missing.

Anti-jihadist militia leader Shehu Mada had told AFP that women from displacement camps were "rounded up by ISWAP insurgents" on Friday.

"Some of the women were able to escape and returned," said Mada, who helped conduct a headcount which found "47 women from the wood-collecting mission could not be accounted for".

Usman Hamza, another anti-jihadist militia leader, confirmed the account.

Borno State police spokesman Nahum Daso Kenneth has said an attack took place at around four pm (1500 GMT) on Friday, but the police could not give a precise figure for the number kidnapped.

Kidnapping is a major problem across Nigeria, which is also grappling with criminal militias in the northwest and a flareup of intercommunal violence in central states.

Last month kidnappers seized at least 35 women returning from a wedding in northwestern Katsina state.

President Bola Ahmed Tinubu came to power last year promising to address insecurity in Nigeria, but critics say the violence is out of control.