Judges on Friday added torture and homicide to the list of charges facing the detained former prison chief of the Khmer Rouge, the communist group that once ruled Cambodia with an iron hand.

The charge against Kaing Guek Eav, also known as Duch, was accepted by judges of the U.N.-assisted tribunal that is attempting to establish accountability for atrocities committed when the Khmer Rouge were in power in 1975-1979.

The communist group is considered responsible for the deaths of an estimated 1.7 million people from starvation, disease, overwork and execution.

Duch, who headed S-21 prison, the Khmer Rouge's largest torture facility, already faces charges of crimes against humanity and war crimes under the statutes of the tribunal.

Five other senior Khmer Rouge members are in the tribunal's custody and face similar charges.

Prosecutors earlier this year said the charges against Duch were insufficient.

They said they also wanted Duch charged with the joint charge of homicide and torture as well as criminal enterprise for actions that occurred inside S-21 prison.

The judges did not agree to charge Duch with joint criminal enterprise, which would have made defendants responsible for the actions of co-defendants on the basis of conspiracy.

About 16,000 men, women and children are believed to have been held at S-21 prison, and only 14 are thought to have survived.

Tribunal spokesman Reach Sambath said Duch will be the first of the six defendants tried. His trial is expected to start early next year.