"The Cameroonian authorities must leave no stone unturned in their pursuit of justice for two women and two children who were brutally murdered by the military," Amnesty said in a statement.

The seven soldiers are due to appear on Tuesday before a military court in the capital Yaounde on charges of joint participation in murder, breach of regulations and conspiracy, according to Captain Cyrille Serge Atonfack, a spokesman for the defence ministry.

The video that went viral on social networks in early July 2018 was initially dismissed as "fake news" by the Cameroonian authorities.

"But Amnesty International revealed credible evidence that the Cameroon military was responsible, and the authorities later announced that the seven soldiers depicted in the video had been arrested and would be prosecuted," the statement said.

Amnesty said it relied on multiple strands of evidence - including expert analysis of the uniforms and weapons used, and linguistic and other contextual clues in speech that gave away the identities and ranks of the soldiers.

"This horrifying video shone a spotlight on the way civilians in Cameroon's Far North have been ensnared in atrocities amid the fight against Boko Haram," said Samira Daoud, Amnesty's West and Central Africa deputy regional director.

"Security forces who are supposed to be protecting people have instead carried out arbitrary detentions and extrajudicial executions," Daoud said.

Cameroon has deployed troops to its Far North to fight Boko Haram jihadists who have crossed over from Nigeria to wage attacks in the neighbouring country.

Cameroon's armed forces have also been accused of abuses in two western regions where anglophone separatists have launched an armed campaign against the predominantly French-speaking state.