Former Cambodian Khmer Rouge minister denied bail

Ieng Thirith has been charged with crimes against humanity for her role in the 1970s Khmer Rouge regime. [AFP]

The United Nations-backed Khmer Rouge tribunal in Cambodia has dismissed a bail request by former Khmer Rouge cabinet minister, Ieng Thirith.

The presiding judge told the court it was necessary for Ieng Thirith to stay in jail as "there are well-founded reasons to believe" that she committed the crimes for which she has been charged.

The court was also told it is suspected Ieng Thirith is a flight risk and that her detention is necessary to protect her against possible revenge attacks from Khmer Rouge victims.

Ieng Thirith, 76, was minister of education and of social affairs during the Khmer Rouge reign from 1975 to 1979.

She is the wife of former Khmer Rouge deputy prime minister and foreign minister Ieng Sary.

Both husband and wife have been charged with crimes against humanity, while Ieng Sary has also been charged with war crimes.

Ieng Thirith was the third of the five Khmer Rouge leaders awaiting trial whose appeals for release have been denied.

Ieng Thirith's lawyers previously insisted the 76-year-old is mentally ill and in poor chronic health.

However, court officials have said doctors deemed her fit to stand trial.

It has taken three decades to start bringing senior officials of the Khmer Rouge, who left up to two million people dead from overwork, starvation, torture or execution, to trial at the joint Cambodia-UN tribunal.

The court was not established until 2006, and the trials of the regime's five surviving senior leaders are not due to begin until later this year.