Suspected Islamist militants killed 40 farmers in an attack on the Dumba community in Nigeria's northeastern Borno State on Sunday, a senior state official said on Monday.

The militants were believed to belong to the armed group Boko Haram and its offshoot Islamic State West Africa Province (ISWAP), who have been waging a deadly insurgency in northeast Nigeria since 2009 that has displaced millions and killed thousands, with Borno at its epicenter.

Sunday's attack comes amid a worsening food crisis in Borno, exacerbated by flooding in September and years of insecurity and displacement caused by the insurgency.

Initial reports indicate the farmers strayed outside a security corridor set up by the military, venturing into an area known for insurgent activity and strewn with landmines, Usman Tar, commissioner of information said.

Security forced were looking for any farmers who had escaped the attack, Tar added.

Borno Governor Babagana Zulum condemned the attack in a statement, calling on the military to "track and deal decisively with the perpetrators"

He said the attack will be investigated and asked farmers and fishermen in the area to operate within the safe corridors demarcated by the military.

Boko Haram and ISWAP have stepped up attacks in Borno since the turn of the year, with a failed ambush on a military patrol last week leaving 34 militants dead. Six soldiers were killed in action.

Reuters