Israel has confirmed it jailed a foreigner in solitary confinement on security grounds who later committed suicide, as Australia admitted Thursday it knew one of its citizens had been secretly held.
The man, identified by Australian media as Mossad agent Ben Zygier, known as "Prisoner X", died in a secret prison near Tel Aviv in 2010 in a case Israel went to extreme lengths to cover up, imposing media gag orders.
Israel broke its silence after the Australian Broadcasting Corporation said the man was a dual Australian-Israeli citizen and reported that he was a spy for Israel's intelligence agency.
"For security reasons the man was held under a false identity although his family was immediately informed of his arrest," Israel's justice ministry said.
The man was found dead in his cell and a judicial inquiry ruled he took his own life, the ministry added 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."
But other details of the case remained under a gag order, leaving local media obliged to quote foreign reports.
Australian Foreign Minister Bob Carr initially said he only became aware of the man's incarceration after his death, but on Thursday admitted the government knew of his detention at the time.
He told a parliamentary committee the information was gathered through intelligence channels.
"They provided the name of the citizen, in relation to serious offences under Israeli national security legislation," he said, adding that Canberra sought assurances that he was not being mistreated.
He said at no stage did the government receive any request for consular support, adding that he would determine Canberra's next step after receiving a full report from his department into the case.
"With the benefit of that full report, I'll determine what representations to the government of Israel are most useful," he said.
The story first emerged in June 2010 when Israel's Ynet news website briefly ran a report 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 through Australia's public broadcaster.
Israeli media did report that Prime Minister Benjamin Netanyahu had 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.
Shortly afterwards, three MPs raised questions over the issue in parliament, effectively sidestepping the censor in a move that forced a slight easing of the reporting restrictions.
While Israel has not revealed the charges, The Australian newspaper suggested he was detained for treason.
It cited Israeli Army Radio as saying: "Why was he interned? The suspicion is because of treason against Israel."
The newspaper's foreign editor, who interviewed Netanyahu last year, said for a Mossad agent to end up in jail something serious must have happened.
"If a former Mossad agent has ended up in an Israeli prison, this can only indicate that something has gone terribly wrong," Greg Sheridan wrote.
The Sydney Morning Herald reported that Zygier was being investigated by Australia's overseas espionage agency ASIS, which suspected him of using his Australian passport to spy for Israel.
The Herald said he was one of at least three dual Australian-Israeli citizens who emigrated to Israel in the past decade whose cases were probed.
It said that in each case the men used the passports to travel to Iran, Syria and Lebanon -- countries that do not allow Israelis to enter.
When the newspaper confronted Zygier in early 2010, he angrily denied he worked for Mossad.
"I have never been to any of those countries that you say I have been to," he said at the time.
"I am not involved in any kind of spying."