Loading As well as targeting politicians, Chinese authorities were working to win influence in social, business and media circles, he said. "Espionage and foreign interference is insidious. Its effects might not present for decades and by that time it's too late. You wake up one day and find decisions made in our country that are not in the interests of our country," Mr Lewis said. "Not only in politics but also in the community or in business. It takes over, basically, pulling the strings from offshore." Mr Lewis was the director-general of security for five years as head of ASIO, the intelligence agency whose primary job is to guard against foreign interference.

He did not single out China during his term in office. When he spoke of malign state actors posing an "existential" threat to Australia, it was a generic reference to foreign governments. But in the post-retirement interview, he said while it was not only China that preoccupied the Australian authorities, it was "overwhelmingly" China. Loading Replay Replay video Play video Play video Covert foreign intrusion into the heart of Australian politics was "something we need to be very, very careful about", he said in the interview for the forthcoming Quarterly Essay, Red Flag: Waking up to China's challenge, to be published on Monday. "One spectacular case in NSW was Sam Dastyari. It's quite clear to me that any person in political office is potentially a target. I'm not trying to create paranoia, but there does need to be a level of sensible awareness.

Loading "When people talked about [how to define foreign interference in] our political system, I used to get the comment, 'We will know it if we see it'. But not necessarily. Not if it's being done properly. There would be some I don't know about." Former Labor senator Sam Dastyari quit Parliament in 2017 after a series of revelations about his links to Chinese Communist Party-aligned interests in Australia. Mr Lewis, formerly Australia's inaugural national security adviser and one-time head of Australia's Special Forces as well as a previous ambassador to Belgium and NATO and secretary of the Defence Department, said the political funding system was especially vulnerable and called for its reform. "I do worry about the issue of financing political parties," he said. "We need a mechanism that maintains parties free of foreign influence."

The Turnbull government, with Labor's support, passed laws against foreign interference in 2018. Then prime minister Malcolm Turnbull named Russia and North Korea when he introduced the bills to parliament, but hinted clearly at the primary threat: "Media reports have suggested that the Chinese Communist Party has been working to covertly interfere with our media, our universities and even the decisions of elected representatives right here in this building. We take these reports very seriously." Beijing maintains that it does not spy or intrude on Australia. Even after a Chinese diplomat, Chen Yonglin, defected to Australia in 2005 and warned of the Chinese government's infiltration strategy, the Chinese authorities insisted such claims were baseless and malicious. After he defected from his post as first secretary for political affairs in China's consulate-general in Sydney, Mr Chen wrote that "the Communist Party of China had begun a structured effort to infiltrate Australia in a systematic way". Mr Lewis said Australia's first line of defence was the community: "We need a more prepared community but we have a way to go yet. ASIO can't do it by itself. ASIO is very dependent on the community to be alert, but not paranoid."