The UN-backed genocide tribunal in Cambodia has rejected a bail request from former Khmer Rouge prison chief Kaing Guek Eav, also known as Duch.
Duch (centre) ran the Tuol Sleng jail, known as a 'killing machine'
Duch was the first of five senior Khmer Rouge officials to be arrested and charged by the international court.
His bail hearing last month was the court's first public session.
The Khmer Rouge regime, which ruled Cambodia between 1975 and 1979, is blamed for more than one million deaths in its four years in power.
Duch, who is now in his 60s, ran the notorious Tuol Sleng jail in Phnom Penh under the Khmer Rouge, and is accused of overseeing the torture and killing of 16,000 people.
He was arrested and detained in July, but on 20 November his lawyers appealed for bail on the grounds that he was held without charge under the jurisdiction of another court for eight years.
WHO WERE THE KHMER ROUGE?
Maoist regime that ruled Cambodia from 1975-1979
Founded and led by Pol Pot, (above) who died in 1998
Abolished religion, schools and currency in a bid to create agrarian utopia
Brutal regime that did not tolerate dissent
More than a million people thought to have died from starvation, overwork or execution
After an hour of deliberations on Monday, Chief Judge Prak Kimsan announced the court's dismissal of the appeal, citing the prosecution's argument that Duch might try to flee.
Five senior Khmer Rouge officials are now in the custody of the tribunal.
Those also facing charges include Nuon Chea, second-in-command of the late Khmer Rouge leader Pol Pot, the former foreign and social affairs ministers Ieng Sary and Ieng Thirith, and former head of state Khieu Samphan.
Their trials are expected to begin next year.