At least 110 people were killed in a weekend attack on farm workers in northeast Nigeria that was blamed on jihadists, the UN humanitarian coordinator in the country said on November 29, making it the deadliest raid on civilians this year.

The attack, in a state gripped by a jihadist insurgency for more than 10 years, took place the same day as long-delayed local elections in the state.

Edward Kallon said in a statement: “I am outraged and horrified by the gruesome attack against civilians carried out by non-state armed groups in villages near Borno state capital Maiduguri.

“At least 110 civilians were ruthlessly killed and many others were wounded in this attack.”

Initial tolls indicated 43 and then at least 70 dead from November 28’s massacre.

Some locals blamed the attack on Boko Haram fighters, but Bulama Bukarti, an analyst with the Tony Blair Institute, said the rival Islamic State-affiliated Islamic State West Africa Province (Iswap) were more active in the area.

“ISWAP is the likely culprit,” he tweeted.

Kallon, in his statement, said: “The incident is the most violent direct attack against innocent civilians this year.

“I call for the perpetrators of this heinous and senseless act to be brought to justice.”

The violence centred on the village of Koshobe near the Borno state capital Maiduguri, with assailants targeting farm workers harvesting rice fields.

One pro-government anti-jihadist militia said the assailants tied up the labourers and slit their throats.

Kallon said the assailants – “armed men on motorcycles” – also targeted other communities in the area.

“Rural communities in Borno state are facing untold hardships,” he added, calling for more to be done to protect them and to head off what he said was a looming food crisis there.

EU foreign policy chief Josep Borrell tweeted his reaction on November 29, saying he was “deeply shocked by yet another horrific attack targeting innocent civilians” in the region.

“We have to continue our collective engagement against terror and violence to provide peace, security and stability for all people in Africa,” he said.

Borno governor Babaganan Umara Zulum attended the burial on November 29 in the nearby village of Zabarmari of 43 bodies recovered on November 28, saying the toll could rise after search operations resumed.

The victims included dozens of labourers from Sokoto state in northwestern Nigeria, roughly 1,000km away, who had travelled to the northeast to find work, it said.

Six were wounded in the attack and eight remained missing as of November 28.

Kallon, citing “reports that several women may have been kidnapped”, called for their immediate release.

Nigerian President Muhammadu Buhari condemned the attack on November 28, saying: “The entire country has been wounded by these senseless killings.”

Neither the president’s statement nor November 29’s reactions from the EU and the UN mentioned either Boko Haram or Iswap by name.

But both groups have been active in Borno state, their attacks having forced the postponement of locations in Borno state, which finally took place on November 28.