Gunmen believed to be ethnic Fulani herders have killed a policeman and 19 civilians and torched homes in Nigeria's northeastern Adamawa state in a spat over grazing rights, the police said Monday.

They said it appeared to be revenge attacks following a row over destroyed crops.

"We lost a DPO (Divisional Police Officer‎) and 19 civilians in his area of jurisdiction when they came under attack by Fulani herdsmen in Girei district," police spokesman Othman Abubakar told AFP.

The senior police officer with his team were "responding to a distress call from the communities under attack to restore calm following an invasion by the armed herdsmen", he said.

Local media reports gave a much higher death toll of 30, including the police officer following the raids on Sunday morning.

The herders attacked the farming hamlets of Demsare, Wunamokoh, Dikajam and Taboungo following a feud between some herders and farmers over destruction of farm crops, Abubakar said.

The villages are in Girei municipality, less than 20 kilometres (12 miles) from state capital Yola.

The raiders looted food supplies and set fire to homes before fleeing, Abubakar said. One suspect was arrested and an investigation has been launched, he added.

Adamawa is one of three states in the northeast apart from Borno and Yobe ‎worst hit by attacks from Boko Haram Islamists whose insurgency has claimed more than 17,000 lives and displaced more than 2.6 million since 2009.

The state which borders Borno, Boko Haram's spiritual home and stronghold, has seen a drastic drop in Boko Haram attacks in recent months after sustained military campaigns against the group.

However, the raids on the four communities had nothing to do with Boko Haram insurgency, the police spokesman said.

"This is purely a communal unrest between farmers and herdsmen," he said.

Disputes between nomads‎ and farmers over grazing and watering rights are common in northern and central Nigeria leading to frequent deadly flare-ups.

The problem has persisted despite interventions by state governments and community leaders who tried to broker truce between the two sides and ending the cycle of deadly attacks and reprisals.
Source: AFP