In a highly suspected Boko Haram attack in Nigeria's Borno state, at least 50 people were killed.

At least 50 people were murdered by militants on Sunday in the town of Rann in Borno state, Nigeria's northeastern corner near the Cameroon border, witnesses told Reuters by phone on Monday.

Nigeria's northeast, particularly Borno state, has been the epicentre of an insurgency led by the militant Islamist organisation Boko Haram since 2009. According to the United Nations, assaults and the resulting humanitarian disaster have displaced millions of people and killed 350,000 people.

Boko Haram has divided over time, with an active offshoot known as Islamic State West Africa Province claiming responsibility for assaults in Nigeria.

Locals accused Boko Haram for the latest incident. A request for response from Army spokesperson Brigadier General Onyema Nwachukwu was not immediately returned.

"We are all in pain over the killing of our innocent people who were working on their farmland. ... We buried 50 people today in Rann. They were clearing their farmlands ahead of the rainy season, while others went for firewood, "According to Harun Tom, a local farmer.

A sight of devastation was detailed by Agid Muhammad, a farmer who had returned to Rann after residing in an internally displaced persons camp.

"A large number of Boko Haram on motorcycles armed with guns and machetes surrounded our people who were working on their farms and held them hostages before killing them one by one," Muhammad claimed, adding that his uncle was still missing.

"They were tied with rope and slaughtered. As I'm speaking to you, many people aren't accounted for."