Prime Minister Malcolm Turnbull has declared he will not back away from foreign interference laws which have stoked the ire of China.

Mr Turnbull said on Friday he remains "absolutely committed" to the legislation and would never take a backward step from protecting Australia's democracy and sovereignty.

"My job is to stand up for Australian democracy and ensure that it is not interfered with," he told reporters on the NSW Central Coast.

"If there are foreign interests or governments or political parties that wish to have a voice, then they should do so openly and transparently."

The country's top intelligence chief has warned there are more foreign spies operating in Australia with the ability to inflict "catastrophic harm" than during the Cold War.

Duncan Lewis, director-general of the Australian Security Intelligence Organisation, has painted a bleak picture of foreign interference against Australia occurring on an "unprecedented scale".

Mr Lewis has warned countries are trying to access classified information about the nation's global alliances and military, economic and energy systems.

"Espionage, interference, sabotage and malicious insider activities can inflict catastrophic harm on our country's interests". (AAP) (AAP)

And he has urged senators to pass the government's proposed foreign interference laws, saying the "grim reality" was there were more foreign intelligence officers now than during the Cold War.

"Espionage, interference, sabotage and malicious insider activities can inflict catastrophic harm on our country's interests," Mr Lewis told a Senate estimates hearing on Thursday night.

"It undermines potentially our sovereignty, our security and our prosperity."

Mr Lewis said foreign actors were attempting to covertly influence and shape the views of the Australian public, its media and officials in the Australian government, as well as members of diaspora communities.

Senators were told these efforts could have an immediate impact, but in some cases the harm may not materialise for decades.

"This is not a theoretical proposition," Mr Lewis said.

"The reality is that acts of espionage and foreign interference are occurring against Australian interests, both in Australia and overseas."

Asked about the potential fallout from a Liberal backbencher's decision to accuse a political donor of involvement in a bribery scandal, Mr Lewis said it would not damage international intelligence partnerships.