Tunis: The Tunisian public prosecution will not appeal against a court ruling to drop a case of possible indecency against a young woman allegedly raped by policemen, the justice ministry said, denying earlier reports.

The case had sparked a storm of protest in Tunisia and earlier Monday the woman's lawyer said she had been notified that the public prosecution would appeal last week's court ruling.

Her announcement was confirmed by justice ministry spokesman Adel Riahi but later an adviser to the minister added to the confusion by denying that an appeal had been lodged.

"The prosecution made no such appeal concerning the woman and her friend," said the adviser, Fadel Saihi.

Defence attorney Bochra Belhaj Hmida had told AFP earlier: "We just found out this morning that the prosecution has lodged an appeal. It is their right, legally, there's nothing that can be said about that."

Justice ministry spokesman Riahi confirmed the appeal, saying: Yes, that is the case."

Neither Belhaj Hmida nor Riahi were able to say why the prosecution would appeal the ruling and later both were also unable to say why the decision was scrapped.

But a source at the Tunis first instance court told AFP that the prosecution apparently "wanted to appeal the court ruling but finally did not do so."

"I don't understand this back and forth," said the source who declined to be identified.

Last week a Tunis judge dropped the case against the 27-year-old woman, whose identity has been kept secret, while two accused officers are to face rape charges and a third for extortion.

The rape victim faced possible indecency charges with her fiance based on the testimony of the alleged rapists, policemen who say they took the couple by surprise in an "immoral position" just before the alleged attack.

A judicial source has previously said that the police had taken the couple by surprise as they were having sex in their car.

Two of them then took the woman to a police car, where they raped her in turn, while a third restrained and tried to extort money from her fiance at a bank cashpoint, the source added.

Last month a magistrate had questioned the woman, alleged raped on September 3, to decide whether she was to be charged with indecency, which could carry a six-month prison sentence.

The case triggered indignation in Tunisia, with NGOs, media and opposition figures saying the proceedings had transformed the victim into the accused and reflected the Islamist-led government's policy towards women.

Prime Minister Hamadi Jebali, from the ruling Islamist party Ennahda, said in October that the policemen, arrested shortly after the incident, would be "severely judged".

But he also said there may be a case of indecency to answer.

However, President Moncef Marzouki in October offered a state apology to the woman.

Since the Islamists' rise to power in 2010 revolution, feminist groups have accused police of regularly harassing women, by challenging them over their clothing or if they go out at night unaccompanied by family members.