YAOUNDE (Reuters) - The Cameroonian government is investigating a video circulated online that appears to show men in military uniform shooting dead two women and two children for being suspected members of the Islamist group Boko Haram.

The shaky video, shared more than 90,000 times on Twitter, shows two women, one with an infant strapped to her back, being led by a group of uniformed men across a patch of dusty scrubland.

“You are BH, you are going to die,” said one French-speaking man in aviator sunglasses and khaki attire, hitting a woman across the face. BH is short for Boko Haram, which for nine years has been fighting to carve out an Islamic caliphate centered in northern Nigeria.

The women are blindfolded and told to sit down alongside their children. Moments later, two men step back, level their rifles and fire a series of rounds.

Reuters was unable to verify the authenticity of the video, including when and where it was filmed.

Government spokesman Issa Tchiroma Bakary said the men in the footage appeared not to be Cameroonian army soldiers. Their weapons and uniforms were not standard issue for the Cameroonian army in the north, he said.

“The video ... is nothing but an unfortunate attempt to distort actual facts and intoxicate the public. Its sincerity can be easily questioned,” Bakary told journalists late on Wednesday, describing the clip as “fake news” and an act of “gross misinformation”.

He said President Paul Biya had ordered an investigation into the footage.

Army spokesman Colonel Didier Badjeck also described the video as “fake news”, according to local media. Reuters could not immediately reach Badjeck for further comment.

However, Amnesty International said it had “gathered credible evidence that it was Cameroonian soldiers depicted in a video carrying out the horrific extrajudicial executions.”

That evidence included analysis of the weapons - especially a Gilil, an Israeli automatic rifle that is rare in Africa but used by a small section of the Cameroonian army - their speech and uniforms, and some corroborating witness testimonies, Amnesty said.

“It is imperative that a proper, impartial investigation is undertaken and those responsible for these abhorrent acts are brought to justice,” Samira Daoud, Deputy Director of the rights group’s West Africa office said in the statement.

The Cameroonian army is fighting insurgencies on two fronts: against Anglophone separatists in the heavily forested west and Boko Haram in the arid north.

Rights groups have accused the army of mistreating civilians and opposition fighters, charges the army and the government deny. Last year, Amnesty International said the army tortured suspected Boko Haram fighters.

In the English-speaking western regions, soldiers have burned villages and killed civilians as they try to quell a growing secessionist movement, according to local residents contacted by Reuters earlier this year. The army rejected those accusations and said it respected human rights.

The conflicts have been destabilizing factors in the cocoa- and oil-producing country which has been run by Biya for 36 years. Presidential elections are set for October.