The prosecution appealed a Trial Chamber decision released on Thursday, requesting the Supreme Court Chamber (SCC) require 80-year-old Ieng Thirith to comply with release conditions proposed by the prosecution.

"The Co-Prosecutors fully agree with the Trial Chamber that Ieng Thirith should be released from detention … [but] are of the view that her release should not have been unconditional," the prosecution said in a statement on Friday.

Ieng Thirith, former Minister of Social Affairs during the Khmer Rouge regime - which ruled Cambodia between 1975 and 1979 - has been accused of genocide, crimes against humanity and grave breaches of the Geneva Conventions.

In their decision the Trial Chamber reaffirmed that, based on expert findings, Ieng Thirith's long and short-term memory loss ensured her inability to "understand sufficiently the course of proceedings" to allow her to properly instruct counsel and participate meaningfully in her defense.

Experts consistently found Ieng Thirith suffers from a progressive, dementing illness - most probably Alzheimer's disease - and her condition is unlikely to improve, the Chamber said.

"As there appears to be no reasonable possibility that the accused Ieng Thirith may recover her cognitive function such that she will be fit to stand trial in the foreseeable future, the Trial Chamber finds that the accused's continued detention under the present circumstances would therefore violate her basic rights," the decision read.

The tribunal is known officially as the Extraordinary Chambers in the Courts of Cambodia.

ECCC public affairs officer Yuko Maeda said the SCC had two days to decide on a prosecution request to stay Ieng Thirith's release.

Defendant 'unfit' for trial

In November, the Trial Chamber found Ieng Thirith unfit to stand trial, stayed proceedings against her, severed her charges from Case 002 and ordered her unconditional release. On appeal in December, a majority of the SCC annulled the release order and ruled Ieng Thirith should receive six months of treatment after which her fitness to stand trial would be reviewed.

In August, three experts appointed to reassess Ieng Thirith testified that she suffered from "moderate to severe" dementia that her condition appeared to have declined and that no existing treatment could improve it.

The prosecution argued Ieng Thirith's release should be subject to conditions, including that she surrender her passport, reside at a specified address, undergo six-monthly medical examinations and weekly safety checks, and not contact witnesses, experts, victims or accused before the court, except her husband Ieng Sary.

The Trial Chamber found it could not exercise jurisdiction over Ieng Thirith while proceedings against her were stayed, it had no legal basis to impose "coercive conditions" or judicial supervision on her release and such conditions would likely be "impracticable and unenforceable" given her diagnosis.

However, it "reminded" Ieng Thirith to refrain from interfering with witnesses, experts, victims or accused - except Ieng Sary - and "requested" she not speak with media, remain in Cambodia and notify the court of a change in address. The Chamber noted the charges against Ieng Thirith were not withdrawn.

The prosecution said in their statement the Trial Chamber had legal authority to apply "limited, reasonably necessary and proportionate restrictions" on Ieng Thirith as it held there was a remote possibility of a trial.

Diana Ellis, international co-counsel for Ieng Thirith, told DW via email that the defense would respond to the appeal.

"It is of particular concern that they [the prosecution] have requested a stay of Ieng Thirith's release which if granted will cause her to be detained for a further period," she wrote.

Observers say decision correct

Clair Duffy, a tribunal monitor for the Open Society Justice Initiative, told DW the decision that Ieng Thirith was unfit and should be released was "correct" and the remaining issue was "very technical."

"There are very few cases for the court to look to that are going to be very helpful."

"Even though other accused have been released and some with conditions … the circumstances have been different."

Anne Heindel, a legal adviser for the Documentation Center of Cambodia, said the SCC would have to decide if Ieng Thirith could ever be tried.

"If there is no chance that she could ever get to trial then the Trial Chamber is correct in releasing her unconditionally," she said, adding that if Ieng Thirith was released, the decision had to properly be explained to the public.

Proceedings in Case 002 are underway, involving Nuon Chea, 86, former deputy secretary of the Communist Party of Kampuchea; Ieng Sary, 86, former deputy prime minister for foreign affairs; and ex-head of state Khieu Samphan, 81.