Twelve American soldiers are facing charges over a secret "kill team" that allegedly blew up and shot Afghan civilians at random and collected their fingers as trophies.

According to The Guardian, five of the soldiers are charged with murdering three Afghan men who were allegedly killed for sport in separate attacks this year. Seven others are accused of covering up the killings and assaulting a recruit who exposed the murders when he reported other abuses, including members of the unit smoking hashish stolen from civilians.

The killings were allegedly carried out by members of a Stryker infantry brigade based in Kandahar province in southern Afghanistan.

According to investigators and legal documents, discussion of killing Afghan civilians began after the arrival of Staff Sergeant Calvin Gibbs at forward operating base Ramrod last November.

Other soldiers told the army's criminal investigation command that Gibbs boasted of the things he got away with while serving in Iraq and said how easy it would be to "toss a grenade at someone and kill them".

One soldier said he believed Gibbs was "feeling out the platoon".

Investigators said Gibbs, 25, hatched a plan with another soldier, Jeremy Morlock, 22, and other members of the unit to form a "kill team".

While on patrol over the following months they allegedly killed at least three Afghan civilians.

The Army Times reported that a least one of the soldiers collected the fingers of the victims as souvenirs and that some of them posed for photographs with the bodies.

Five soldiers - Gibbs, Morlock, Holmes, Michael Wagnon and Adam Winfield - are accused of murder and aggravated assault among other charges. All of the soldiers have denied the charges. They face the death penalty or life in prison if convicted. (ANI)