Australian universities and businesses have been warned they face an unprecedented threat of foreign interference.
ASIO boss Mike Burgess has sounded the alarm on the rise of espionage, interference and right-wing extremism.
Mr Burgess also revealed ASIO had uncovered a sleeper agent running a major spy ring.
"The level of threat we face from foreign espionage and interference activities is currently unprecedented," he said in his annual threat assessment.
"It is higher now than it was at the height of the Cold War."
Home Affairs Minister Peter Dutton told parliament Mr Burgess' speech was a stark reminder of the threats Australia faced.
"We are facing an unprecedented level of threat both in terms of those terrorist cells and people that would conduct themselves in the dark art of foreign interference," he said.
He wanted to make sure intelligence agencies had enough resources to deal with these threats.
Mr Burgess said in recent years ASIO had been consistently detecting and regularly disrupting espionage operations in Australia.
New espionage and foreign interference laws were delivering dividends, with foreign intelligence services forced to change their tactics, he said.
"Wherever possible, ASIO seeks to 'detect and protect' before damage is done."
He said ASIO had recommended visa cancellations when foreign agents had been identified trying to travel to Australia, and foreign agents had been intercepted at Australian airports.
He gave the example of a foreign "sleeper" who had quietly built community and business links while secretly maintaining contact with his offshore handlers.
"The agent started feeding his spymasters information about Australia-based expatriate dissidents, which directly led to harassment of the dissidents in Australia and their relatives overseas.
"In exchange for significant cash payments, the agent also provided on-the-ground logistical support for spies who travelled to Australia to conduct intelligence activities."
However, ASIO disrupted the operation.
Mr Burgess also made mention of right-wing extremists, saying ASIO advice earlier this year led to an Australian being stopped from leaving the country to fight with an extreme right-wing group.
Prime Minister Scott Morrison said ASIO has been looking at right-wing extremists for a long time.
"Terrorism and extremism come in many different flavours and many different colours and it's important that all of our efforts are keeping Australians safe," he told reporters.
Mr Dutton said whether extremists were left or right-wing - or whether foreign agents were from China, Russia or Iran - was of no consequence to him or Australia's national security agencies.
Australian Associated Press