Unmasking the former politician who betrayed the nation by helping a foreign spy ring would hurt future intelligence gathering, the spy chief says, revealing the person was a member of parliament at the time.
ASIO director-general Mike Burgess last week unveiled a former politician had helped a foreign spy ring and sold out their country.
It's led to wild speculation about who the person could be and at what level of politics they were at.
Mr Burgess has since revealed they were a serving MP during the time of the allegations but kept what parliament - state, territory or federal - they served in under wraps.
"I can understand a view that it's in the public interest, but I don't agree with that," he told SBS in an interview published on Sunday.
Revealing the name could jeopardise future intelligence gathering as the foreign unit tasked with spying on Australia "might figure out how I worked out who it was", Mr Burgess said.
ASIO had been following the activities of the foreign spy ring for "less than a decade but a number of years".
While a person's motivation could span financial gain, political beliefs, feeling indebted to a foreign organisation they had cultivated a relationship with or blackmail and coercion, Mr Burgess would not reveal what drove the turncoat.
He said he had made his point by raising awareness of the issue.
"If anyone's looking for a political point score by naming one individual, I'd encourage them to think carefully about what they're asking for," he added.
The identity of the person was beside the point, cabinet minister Jason Clare said.
"The point is that there's evidence here from the head of ASIO that says another country has interfered in Australian politics, contacting a politician," he told Sky News on Sunday.
"He's made the point that this is still a real threat and that we need to be on our guard against this.
"This is not a game of guess who, this is about keeping the country safe - the fact that this happened in the first place is deadly serious."
