Rights group says it has authenticated a video showing separatists with the decapitated head of a policeman.

Amnesty International says it has authenticated a video showing English-speaking separatists in Cameroon with the decapitated head of a policeman and condemned a “horrific escalation of violence” in the anglophone regions.

The clip showed the policeman’s head, with bruises on it, on blood-soaked white cloth with what “could be his genitalia” placed nearby, the UK-based rights group said in a statement on Tuesday.

It said its forensic experts had authenticated the video, as well as another believed to be a continuation of the first, in which a voice can be heard saying that the separatists had taken the officer’s rifle.

Separatist unrest in Cameroon’s two minority English-speaking regions – the Northwest and Southwest – has left hundreds dead and displaced about 200,000 people since late 2016.

Years of resentment at perceived discrimination at the hands of Cameroon’s majority French speakers have led to almost daily acts of violence and retribution, triggering an army crackdown.

Amnesty said it was not able to independently confirm the exact location where the videos were shot, but analysis suggested it might be in the area of Belo, in the Northwest region.

“The brutal attacks against ordinary people and security forces are further proof of the horrific escalation of violence in Cameroon’s anglophone regions,” Amnesty said.

Last month, Amnesty said a video shot in the village of Achigaya in Cameroon’s Far North region showed the “brutal killings” of at least a dozen unarmed people by the country’s security forces.

It alleged at the time that the “horrifying” video provides “credible evidence” that “Cameroon’s armed forces have committed grave crimes against civilians”. Cameroon’s government later said it would launch an investigation.

On Tuesday, Samira Daoud, Amnesty’s deputy regional director for West and Central Africa, said the situation in the anglophone regions was “becoming increasingly desperate with no one spared from the violence which is spiralling out of control”.

The rights group said up to 400 “ordinary people” have been killed over the past year by both the security forces and the armed separatists.

Separatists have been demanding a separate English-speaking state they call Ambazonia and threatening to disrupt an October 7 election in the largely French-speaking country.

Hundreds of families have been fleeing the regions in advance of the forthcoming elections.

President Paul Biya announced in July he would seek a seventh term in October’s elections.