Militants of the Boko Haram fundamentalist group have killed at least 40 people on a farm in Borno state in northeast Nigeria, three sources told Reuters on Saturday.

The attack, at Kwashebe Zamarmari in the Jere local government area, happened late morning local time as the workers were harvesting rice, according to a village leader, a local fighter with the Zamarmari group and a police source.

A search by the authorities for the attackers has been mounted.

The military and police did not immediately respond to requests for comment.

Boko Haram and Islamic State West Africa Province are both active in northeast Nigeria, where insurgency has reigned for a decade.

Food prices in Nigeria have risen substantially this year, in part due to insecurity in food-producing areas, according to politicians. Flooding in northwest Nigeria earlier this year also destroyed thousands of hectares of rice paddy.