At least 43 people have been killed in what the Nigerian president has described as an “insane” attack in north-east Nigeria on Saturday.
The attackers tied up agricultural labourers working in rice fields and slit their throats near Maiduguri, the capital of Borno state, reports say.
This is one of the worst attacks in recent months in a region where the Boko Haram and the Islamic State West Africa insurgent groups are active.
No-one has yet claimed responsibility.
“I condemn the killing of our hard-working farmers by terrorists in Borno state. The entire country is hurt by these senseless killings. My thoughts are with their families in this time of grief. May their souls rest in peace,” said President Muhammadu Buhari.
President Buhari also described “the terrorist killings as insane”, according to his spokesman Garba Shehu.
“We have recovered 43 dead bodies, all of them slaughtered, along with six others with serious injuries,” a local militiaman who helped the survivors told the AFP news agency.
At least another six farm workers are thought to have been abducted.
The victims were labourers from Sokoto state in north-western Nigeria, roughly 1,000 km (600 miles) away, who had travelled to the north-east to find work, another militiaman told AFP.
The farmers “were attacked because they had on Friday disarmed and arrested a Boko Haram gunman who had been tormenting them”, a member of the local parliament, Ahmed Satomi, told newspaper Premium Times.
Correspondents say farmers have previously been attacked by Boko Haram, which suspects them of passing on information to the military.
Last month, Boko Haram fighters killed 22 farmers working on irrigation fields in two separate incidents.
On Sunday, six soldiers were reportedly killed in a jihadist ambush near the town of Baga in Borno State, says the BBC’s Chris Ewokor, in Abuja.
The soldiers were on their way to the area to boost security at a food distribution depot for people displaced by the conflict.