Spy boss explains why he won't name ex-politician who 'sold out' Australia

On Wednesday, Australian Security Intelligence Organisation director-general, Mike Burgess, revealed foreign spies had recruited a former politician several years ago.

The former politician had gone as far as to suggest bringing an Australian prime minister's family member into the orbit of the spy ring - a plan which did not eventuate.

The example, delivered as part of his annual threat assessment, set off a storm of speculation and calls from within Parliament to out the "traitor".

In a statement on Thursday evening, Mr Burgess explained why he would not provide further details.

"It is an historic matter that was appropriately dealt with at the time," the director-general said.

"The individual is no longer of security concern.

"In accordance with long-standing practice, ASIO will not publicly discuss individuals or provide operational details."

Mr Burgess said there were "multiple reasons" for this, including that to provide further detail would risk exposing Australian sources and capabilities.

"In this case, while we want the foreign intelligence service to know its cover is blown, we do not want it to unpick how we discovered its activities."

The spy boss reiterated that while foreign attempts "to interfere in our democratic processes are common, successful interference is not".

"Our democracy remains robust, our parliaments remain sovereign, our elections remain free and the overwhelming majority of our politicians remain thoroughly resistant to even the most sophisticated and subtle approaches," Mr Burgess said.

"I will continue to raise awareness of the threats facing Australia to ensure potential targets can better recognise, resist and report them."

He welcomed the increased awareness following his speech on Wednesday evening, calling this "reassuring".

Meanwhile, Alex Turnbull - son of Malcolm Turnbull - told news.com.au he had been contacted by a group he suspected to be foreign agents, while his father was prime minister.

He said he rejected the approach and referred the encounter to security agencies.

Former treasurer Joe Hockey led the calls demanding the spy chief name the "traitor", to avoid smearing others who had done nothing wrong.

"You cannot have the head of our national security organisation go public with allegations against, or statements of fact against a politician and then not have the guts to name who that person was," he told Sky News.

"A wrap on the knuckles from the head of ASIO is not appropriate, and it's not enough for someone who was a traitor to Australia."

He was backed by Opposition Leader Peter Dutton, and the spokesperson for foreign affairs, Simon Birmingham.

But government ministers stood by the ASIO boss on Thursday, attempting to pull focus back to the threat posed to all politicians through escalating espionage.

"There's probably no level of detail that the Canberra press gallery would be happy with, coming from the director-general of ASIO," Home Affairs Minister Clare O'Neil told the ABC.

"The purpose of the director-general's statement is to elevate public understanding about what foreign interference is and what it looks like. And that is exactly what he's done with his speech yesterday."