A suspected agent of the Israeli spy agency Mossad known as "Prisoner X" was arrested by his own spymasters after leaking information about his work to Australian intelligence services, an Australian broadcaster reported.
Ben Zygier, an Australian-Israeli who died in an Israeli jail in 2010, reportedly gave Australian intelligence officials a comprehensive account of a number of Mossad operations, the sources told the Australian Broadcasting Corporation (ABC) on Monday.
Israel's parliament said it would launch an "intensive" inquiry into Zygier's arrest and death after ABC revealed his identity.
According to ABC, Zygier was found hanged in his cell in Ayalon prison near Tel Aviv in December 2010, in a case Israel went to extreme lengths to cover up.
Israel had imposed a total media blackout on the case, naming Zygier only as "Prisoner X". But it was forced to ease the restrictions after the story made headlines across the world, rendering the local gag order ineffective.
Several newspapers were also reporting that the Australian government knew about Zygier's secret imprisonment in Israel before his death.
The closely-guarded case has raised questions in Australia and Israel about the suspected use by Mossad of dual Australian-Israeli nationals.
Prime Minister Binyamin Netanyahu said on Sunday that shining too much light on intelligence activities can "badly damage" state security.
"I ask everyone: let the security forces continue to work quietly in order that we can carry on living in peace and security in Israel," he said.
ABC reported that Zygier gave Australian Security Intelligence Organisation (ASIO) officials information that included plans for a top-secret mission in Italy that had been years in the making.
It is unknown who initiated the contact with the Australian intelligence services, which came during one of his frequent visits back with his wife and children.
In one of four trips to Australia in the years before his death he reportedly applied for a work visa to Italy.
ABC said it understood Zygier was one of three Australian Jews working for Mossad who changed their names several times, taking out new passports as they travelled in the Middle East and Europe.
Zygier reportedly set up a Europe-based communications company for the Mossad that exported electronic components to Arab countries as well as Iran, a venture that employed the two other dual citizens.
Zygier, who immigrated to Israel in around 2001, is believed to have been arrested in February 2010. He was found hanged in his cell 10 months later despite being under 24-hour surveillance.