Cameroon has admitted that three members of its armed forces were involved in the February killing of 13 civilians, including 10 children, in the country's anglophone area.

The government had previously denied any role in the killings in the region, where English-speaking separatists have been fighting government forces since 2017.

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The February 14 massacre in the village of Ntumbo in Cameroon's Northwest Region left 23 people dead, including 15 children, according to the United Nations, which called it "a shocking episode in the ongoing crisis that has afflicted the country’s North-West and South-West regions for the past three years".

It said nine of the children were under age five and that two of the victims were pregnant women.

In a statement read over state radio on Tuesday, Cameroonian President Paul Biya's office said three soldiers and a vigilante group stormed a separatist base, killing five people, before "discovering that three women and 10 children were killed" in the firefight.

"Overcome with panic, the three soldiers helped by some members of the self-defence group tried to hide the incident by setting fires," the statement said, according to AFP news agency.

The army initially claimed that the deaths were an accident after fuel supplies exploded into flames during a gun battle with separatists, while the president established a commission of inquiry to investigate the killings.

In February, one of the country's two main opposition parties, the Movement for the Rebirth of Cameroon (MRC), issued a statement that said: "The dictatorial regime [and] the supreme head of the security and defence forces are chiefly responsible for these crimes."

Conflict between Cameroon's army and English-speaking fighters seeking to form a breakaway state called Ambazonia began after the government cracked down violently on peaceful protesters complaining of being marginalised by the French-speaking majority.

Rights groups have accused both sides of atrocities in the conflict, which has left more than 3,000 dead, closed schools and clinics, and forced 700,000 people to flee their homes.