KABUL, Afghanistan — A graphic video showing Afghan security forces abusing bound and wounded bodyguards of a powerful northern militia commander arrested by the country’s government emerged on Friday, and it was likely to further stoke widespread protests over the arrest that are already in their 11th day.

The video, filmed by members of the security forces as they were detaining the militia commander from Faryab Province, Nizamuddin Qaisari, and his bodyguards, shows soldiers kicking bloodied detainees in the face and stepping on their heads while smiling and posing for the camera.

The authenticity of the video could not be confirmed, although Afghan government officials have not disputed it.

Patricia Gossman, the senior Afghanistan researcher for Human Rights Watch, said that the video showed the kind of human rights abuses that the Afghan forces had been accused of before, and that the government had failed to hold people accountable.