Israel confirmed Wednesday it imprisoned a foreigner in solitary confinement on security grounds who had committed suicide in 2010, following reports "Prisoner X" was an Australian Jew linked to Mossad.
"The Israel Prisons Service held a prisoner who was an Israeli citizen and also held foreign citizenship. For security reasons the man was held under a false identity although his family was immediately informed of his arrest," the justice ministry said.
The man was found dead in his cell two years ago and a judicial inquiry ruled he had taken his own life, the ministry said in a statement, although it did not reveal his identity or the charges against him.
"Following an extensive investigation it was ruled six weeks ago that it was suicide," said the ministry. "The prisoner was held in jail under a warrant issued by a court."
"Procedures regarding the prisoner were followed by the highest officials at the ministry of justice, and the individual rights of the prisoner were retained, subject to the provisions of the law."
But other details of the case remained under a gag order, leaving local media obliged to quote foreign reports.
The story of the so-called Prisoner X first emerged in June 2010 when Israel's Ynet news website briefly ran a story about a prisoner being held in top secret conditions whose identity and alleged crime were not even known to his jailers.
The story was quickly taken offline and a complete media blackout imposed, but it resurfaced on Tuesday when the ABC, Australia's public broadcaster, identified the mystery prisoner as an Australian man recruited by Israel's spy agency.
Israeli media did report that Prime Minister Benjamin Netanyahu had on Tuesday called an urgent meeting with top editors to ask them to withhold "publication of information pertaining to an incident that is very embarrassing to a certain government agency," Haaretz newspaper said, in a clear allusion to Mossad.
But shortly afterwards, three MPs raised questions over the issue in parliament, effectively sidestepping the censor in a move which forced a slight easing of the reporting restrictions.
In its report, the ABC named the prisoner as 34-year-old Ben Zygier, a Jewish lawyer from Melbourne who moved to Israel in 2001 where he was known as Ben Alon.
It said he was working for Mossad, and that his incarceration was one of the most sensitive secrets of Israel's intelligence community.
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Before his arrest in early 2010, Zygier had been living in Israel for about 10 years and was married to an Israeli woman with whom he had two children, the channel said.
The ABC had no information on why he was arrested but said he was taken to Ayalon prison near Tel Aviv where he was held in virtual isolation.
In December of that year, Zygier was found hanged in his cell, despite the fact it was equipped with state-of-the-art surveillance systems to prevent suicide, it said.
In an ABC interview, Australian Foreign Minister Bob Carr said Canberra only became aware of Zygier's incarceration after his death and said he was troubled by the questions raised by the report.
But on Wednesday he confirmed he had ordered a review of the handling of the case.
According to a report in The Australian, he ordered the review after finding out an Australian diplomat in Tel Aviv had been informed of Zygier's incarceration but "had not passed on the information through the appropriate channels".
It said Carr was unlikely to demand clarifications from Israel without a demand from Zygier's family for an explanation.
But in Israel, the questions were coming thick and fast.
In a letter to the deputy attorney general, the Association for Civil Rights in Israel raised a number of key questions and asked that the scope of the gag order be further limited.
"There is a strong public interest in the reasons behind the prisoner's death, and answers to the following questions: Are we indeed talking about suicide? Was there negligence in the supervision of the prisoner?" it wrote.
Nitzan Horowitz, an MP with the leftwing Meretz, said he had tried to help the anonymous prisoner in June 2010 and had been assured the situation was under control.
"A very senior official from (Attorney General Yehuda Weinstein's) office got back to me and promised me officially that the matter was under full judicial oversight."