A UN-backed court has found the former head of a notorious Khmer Rouge prison guilty of war crime and crimes against humanity and sentenced him to 35 years imprisonment.

The Extraordinary Chamber of the Cambodian Court (ECCC) on July 26 handed down the sentence to Kaing Guek Eav, alias Duch, who ran the prison S-21 and the torture centre in Phnom Penh between 1975 and 1979, when the Khmer Rouge were in power.

Duch will have to serve 19 years in prison as the court took into account the 11 years he has already served and another five years in recognition of his cooperation with the court.

This is the first verdict that the ECCC has returned on a former leader of the Khmer Rouge regime, that is blamed for the deaths of at least 1.7 million Cambodians.

More than 15,000 people were tortured before being sent for execution at the Toul Sleng or S-21 prison and few survived.

A large number of Cambodians from all walks of life, survivors from prison, Buddhist monks and journalists from both in and outside of the country flocked to the ECCC headquarters in Kandal province to witness the sentence, while over 10 million other Cambodians watched it on television.

“Today is a historical day for all Cambodians,” said the ECCC’s spokesman Reach Sambath.

Four other Khmer Rouge leaders face charges of genocide and war crimes. They include the group's top ideologist, Nuon Chea; the former head of State Khieu Samphan, former Foreign Minister Ieng Sary, and his wife, former Social Affairs Minister Ieng Thirith./.