Foreign Minister Bob Carr Wednesday said he was troubled by the mysterious 2010 death in Israel of an Australian prisoner with suspected Mossad ties, but without a complaint there was little he could do.
The story of the so-called Prisoner X first emerged in May 2010 when Israel's Ynet news website ran a story entitled "Who are you, Mr X?".
In the report, it spoke about a prisoner being held in top-secret conditions whose identity and crime were not even known to his jailers.
But the story was quickly taken offline due to an Israeli government gagging order.
The Australian Broadcasting Corporation's "Foreign Correspondent" programme Tuesday identified the prisoner as an Australian national from Melbourne who it said was recruited by Israel's Mossad spy agency.
It named him as Ben Zygier, 34, but said he was known in Israel as Ben Alon.
His body was reportedly flown home for burial a week after he was found hanged in a high-security cell at a prison near Tel Aviv in late 2010.
"Those allegations certainly do trouble me," Carr told the ABC.
"It's never been raised with me. I'm not reluctant to seek an explanation from the Israeli government about what happened...
"The difficulty is I'm advised we've had no contact with his family (and) there's been no request for consular assistance during the period it's alleged he was in prison."
Under international conventions, when a foreigner is jailed or dies, their diplomatic mission must be informed. Carr said Australia only knew of Zygier's incarceration after his death.
The ABC cited a former operative with Australia's overseas spy agency ASIS as saying Zygier's transgression must have been due to "espionage, treachery -- very, very sensitive information that, known to others, would pose an immediate threat to Israel as a nation state".
The Israeli government has gone to extreme lengths to suppress the story, imposing a complete media blackout. But two Israeli MPs on Tuesday questioned the justice minister over the ABC report.
"Can you confirm that this Australian committed suicide in prison under a false name so it wouldn't be revealed he was being detained in Israel?" Arab Israeli MP Ahmed Tibi asked Justice Minister Yaakov Neeman.
Neeman said he was not able to answer "because the justice ministry is not responsible for prisons".
Warren Reed, a former ASIS intelligence operative, told "Foreign Correspondent" that Australians were ideal recruits for Mossad.
"Australians abroad are generally seen to be fairly innocent," he said.
"It's a clean country -- it has a good image like New Zealand. There aren't many countries like that, so our nationality and anything connected with it can be very useful in intelligence work."