Australia's Foreign Minister Bob Carr confirmed for the first time on Wednesday that Australian-Israeli citizen, Ben Zygier - codenamed 'Prisoner X' - who died in a maximum-security Israeli prison in December 2010  had been working for Israel's government, AP reports.
Zygier was found dead in his cell a month after his arrest and detention at a maximum security prison, despite there being high-tech surveillance systems in place intended to prevent suicide.
Following his death, reports have said the Australian-Israeli citizen worked for Israel's Mossad spy agency. 
On Wednesday, Carr reportedly said that Zygier had been working for Israel's government but would not confirm or deny reports that he had worked for Mossad.
According to AP, Carr also raised the possibility of a diplomatic spat if Zygier's Australian passport was used for espionage.
"Certainly if Australian passports were misused here, that's something we are forced to take very seriously," Carr told reporters.
"No country can allow the integrity of its passport system to be compromised. We can't say whether it happened with Mr. Zygier's several passports. I hope the inquiry that takes place ... in Israel can clarify this position," he added.
Israel's government has so far refused to release details about the case but if it is confirmed that Israel used Zygier's passport for intelligence-gathering purposes , Carr says Australia will register "the strongest protest."
On Wednesday, Carr released a report criticizing a lack of communication between Australian officials. The review also found that Zygier was granted regular access to a lawyer and was visited by family members more than 50 times during his imprisonment.
Carr said Australia has asked Israel to provide it with information on the charges Zygier was facing, but Israel has refused because of a gag order.