"I suspect it was something more serious than just sharing information with ASIO," he told ABC radio on Tuesday. "I suspect that's not the reason he ended up in jail."
- Did Zygier leak Mossad info to ASIO?
- Australian AG: No need for ASIO probe
- Knesset committee to probe 'Prisoner X' affair
Downer revealed he once raised with Israel's Foreign Ministry allegations that Mossad was using Australian passports to carry out operations abroad.
"I did warn them that they shouldn't use Australian passports, or false Australian passports," he said, adding the discussion occurred sometime between 2005 and 2007.
Israel "took note" of his concerns, he said.
Meanwhile, the Zygier family has broken its silence and is now demanding that Israel disclose the circumstances of the alleged Mossad agent's death. "We demand that Israel tell us exactly what happened to Ben," a family member told Yedioth Ahronoth's Daniel Edelson.
"We are anxiously waiting for the report of the Israeli inquiry commission to be published."
Australia Jews break silence
Also Tuesday, Australia's Sidney Morning Herald reported that the country's leading Jewish community organization has broken a week-long silence on the case of the death of the Australian-Israel dual national.
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 Ben Zygier.
"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.
On Monday, ABC Australia reported that Zygier, also known as "Prisoner X," was questioned by the Australian Security Intelligence Organization about his connection to the Israeli intelligence agency.
It was after the ASIO interrogation that Zygier was arrested in 2010, the report said; adding that it is believed that he "told ASIO about every aspect of his work with the Israelis."
- Receive Ynetnews updates
directly to your desktop