Prosecutors urged Cambodia's Khmer Rouge tribunal on Friday to confiscate the passport of a former regime leader it is about to free because it has deemed her medically unfit to stand trial.

The release of 80-year-old Ieng Thirith had been expected Friday, but will be delayed at least a few days while the court considers the prosecutors' request to apply several restrictions on her freedom.

Ieng Thirith is one of the most senior surviving leaders of the Khmer Rouge, the genocidal regime that killed an estimated 1.7 million Cambodians during its 1975-79 reign.

The prosecutors said they agreed that Ieng Thirith should be freed from detention but that her release "should not have been unconditional."

"Factors such as national reconciliation and stability, justice, public order and safety must also be given due regard," a statement from the prosecutors' office said.

On Thursday, the United Nations-backed tribunal said it would free Ieng Thirith because she suffers from a degenerative illness, probably Alzheimer's disease. The court said the illness left "no prospect" for her to face trial.

The Sorbonne-educated Shakespeare scholar served as the Khmer Rouge's social affairs minister and was a sister-in-law of the regime's late leader Pol Pot. She is accused of involvement in the "planning, direction, coordination and ordering of widespread purges," and was charged with crimes against humanity, genocide, homicide and torture. She has denied the charges.

The prospect of Ieng Thirith's release drew outrage from Khmer Rouge survivors. They say they have waited more than 30 years for justice and find it hard to feel compassion for her suffering.

The prosecutors asked that mandatory restrictions be applied to Ieng Thirith to prevent her from fleeing or interfering with witnesses, to ensure her safety and public order, and to make sure the court is apprised of the state of her health.

The original order freeing her had merely "requested" her to meet certain conditions, such as not leaving the country.

In addition to surrendering her passport and ID card, the prosecutors proposed, among other conditions, that she make herself available for a "weekly safety check" by the authorities; not contact any witnesses or any of the other accused, aside from her husband; and undergo a medical exam by court-appointed doctors every six months.

"Ieng Thirith will stay in detention while the (tribunal's) supreme court considers the appeal," said tribunal spokesman Neth Pheaktra. If the appeal is accepted, a ruling will be made within 15 days, he said.

Ieng Thirith was one of four aging and frail defendants in Case 002, the court's most high-profile case so far.

The others currently on trial include her husband, 86-year-old Ieng Sary, the regime's former foreign minister. Also on trial are 85-year-old Nuon Chea, the Khmer Rouge's chief ideologist and No. 2 leader behind Pol Pot, and 80-year-old Khieu Samphan, a former head of state.