Australian Security Intelligence Organisation Director-General Mike Burgess said every sector of Australian society was a potential target for foreign interference.

"We see evidence of intelligence services deceptively cultivating politicians at all levels of government (to) advance the interests of the foreign government," he told a Senate estimates hearing in Canberra on Tuesday.

"In the coming weeks, I will write to all Commonwealth parliamentarians to warn they are attractive targets for those trying to steal our secrets and manipulate our decision making."

Under questioning from independent senator Rex Patrick, Mr Burgess said the attempts to curry favour with politicians were coming from multiple countries.

He said foreign intelligence services were adept at knowing at what stage people had been cultivated.

"Sometimes they'll think they can chance their arm and do something more sinister and harmful," the ASIO boss said.

"Other times they recognise this individual won't be subject to that and they won't ask them."

Senator Patrick asked if foreign intelligence were trying to exploit politicians' infidelities, sexual preferences, greed or debt.

"That's one thing but that's not the main game we're seeing," Mr Burgess replied.

He said social media was a rich source of information, but not the only way foreign states found out about Australian politicians.

The ASIO director-general also warned Australia's culturally-diverse communities were being harassed by foreign countries.

"It is unacceptable that people in Australia are being intimidated simply for advocating for democratic reforms or criticising human rights abuses," he said.

Australian Associated Press