At least 16 civilians in Nigeria's north-western Zamfara State have been killed in a military air strike, apparently after being mistaken for criminal gangs.

Residents told local media the victims were members of local vigilante groups and civilians defending themselves from armed gangs notorious for kidnapping people for ransom.

The strikes targeted militant gangs in Zurmi and Maradun areas and the state governor, Dauda Lawal, offered his condolences to the community.

The military has acknowledged conducting air strikes, which it said had dealt "a decisive blow to bandits terrorising villages in the area".

The Nigerian Air Force (NAF) said it was investigating "reports of vigilante losses".

"While the operation successfully eliminated several bandits and led to the recovery of some kidnap victims, the NAF views with grave concern reports of the loss of civilian lives in the course of the operation," it said in a statement.

It said an ongoing "comprehensive investigation" would ascertain the truth of the matter, which would be "communicated to inform and reassure the public".

The AFP news agency quoted a local as saying that the civilians were returning to their villages after chasing away bandits when they were bombed.

The villagers "recovered 16 bodies from the attacks and took several other people with severe injuries to the hospital", Sa'idu Ibrahim was quoted as saying.

Rights group Amnesty International Nigeria put the death toll at 20 and said dozens of others were injured in the attack on Tunga Kara village, and called on authorities to "immediately and impartially" investigate the incident.

"Launching air raids is not a legitimate law enforcement method by anyone's standard. Such reckless use of deadly force is unlawful, outrageous and lays bare the Nigerian military's shocking disregard for the lives of those it supposedly exists to protect," it said in a statement.

In recent years, Nigeria's security forces have been fighting powerful criminal gangs, known as bandits, who have been terrorising north-west and central states. The bandits raid villages, burn homes and kill and abduct residents for ransom.

Several accidental air strikes have occurred in recent months including a Christmas Day attack that killed at least 10 civilians in neighbouring Sokoto state.

In 2023, at least 85 civilians, mostly women and children, attending a Muslim religious gathering at a village in Kaduna state were killed after they were mistaken for bandits.

In January 2017, at least 112 people were killed when a jet struck a camp housing 40,000 people who had been displaced by jihadist violence in a town near the Cameroonian border.