The grave of Ben Zygier
The grave of Ben ZygierReuters

Former Australian Foreign Minister Alexander Downer said Tuesday that Ben Zygier, also known as “Prisoner X”, was not “only” arrested for relaying classified information on the Mossad to Australia's intelligence agencies, but was held for a crime far “more serious.”

"I suspect it was something more serious than just sharing information with ASIO,” Downer told ABC radio on Tuesday, referring to the Australian Security Intelligence Organization. "I suspect that's not the reason he ended up in jail."

The former minister revealed that he had previously brought allegations that the Mossad was using Australian passports to carry out operations abroad to the attention of the Israeli Foreign Ministry.

"I did warn them that they shouldn't use Australian passports, or false Australian passports," he said.

Israel "took note" of his concerns, he added, reflecting on the discussion that reportedly took place sometime between 2005 and 2007.

Meanwhile, Australia’s leading Jewish community organization has broken a week-long silence on the mysterious Zygler case, Australia's Sydney Morning Herald reported Tuesday.

In a statement issued Tuesday, the Executive Council of Australian Jewry welcomed announcements by the Australian and Israeli governments of inquiries into the circumstances surrounding the death of the Australian-Israeli dual national.

"We welcome the fact that the Israeli Parliament's Foreign Affairs and Defense Subcommittee for Intelligence and the Israeli State Attorney's office have both announced that they will be conducting investigations into the circumstances surrounding Ben Zygier's death,'' Executive Council President Dr. Danny Lamm said in a written statement.

Zygier, who immigrated to Israel in around 2001, is believed to have been arrested in February 2010. He was reportedly found hanged with a bedsheet in his cell 10 months later despite being under 24-hour surveillance.