Foreign hackers have reportedly compromised computers in the offices of Prime Minister Julia Gillard and senior ministers, confirming fears of increasing cyber espionage and attack.

Chinese hackers - previously accused of similar attacks on American, French and Canadian computer networks - are said to be among the suspects.

The reported breaches came despite a tightening of the nation's cyber defences through a new security strategy and warnings by the head of the domestic spy agency that computers posed a growing threat.

"Today, we see constant attempts by cyber means to steal the nation's secrets, as well as information vital to the effective operation of critical national industries and infrastructure, not to mention commercial intelligence and criminal fraud," said David Irvine, director-general of the Australian Security Intelligence Organisation (ASIO).

"The cyber world will be a principal mechanism of warfare in the 21st century [and] has the potential to reduce the conventional and nuclear weapons advantage of a country."

Although the breaches could not be independently confirmed and the Government maintained its standard practice of not commenting on intelligence matters, Sydney's Daily Telegraph said the parliamentary computers of at least 10 federal ministers were suspected of being hacked into.

The newspaper said the attacks, beginning last month, were believed to have potentially opened access to several thousand emails.

As well as Ms Gillard's, the targeted computers reportedly included those used by Foreign Minister Kevin Rudd and Defence Minister Stephen Smith.

The Telegraph said the hackers had not broken into the more secure departmental network ministers used for sensitive communications.

The report said Australian intelligence agencies had been alerted by American officials within the CIA and FBI, and that ASIO was investigating.

Four separate government sources confirmed that they had been told Chinese intelligence agencies were among a list of foreign hackers under suspicion, the Telegraph said.

China has previously been accused of attacking security networks in the United States, and of targeting Australian mining giants BHP Billiton, Rio Tinto and Fortesque Metals Group.

Last month Canada's Treasury Board confirmed there had been an unauthorised attempt to penetrate its networks after broadcaster CBC reported China-based hackers had attacked government computer systems.

This month the French Finance Ministry shut down 10,000 computers after hackers using Chinese internet addresses hunted for documents about the G20 group comprising the world's biggest economies, which France is this year chairing.

China has dismissed the allegations as groundless.

Australia has been growing increasingly nervous about its potential vulnerability to cyber attack, with a national interest analysis on membership of the Council of Europe Convention on Cybercrime handed this month to a parliamentary standing committee.

Membership of the convention, the only binding international treaty on cybercrime, has already been discussed with key intelligence partners including the US, Britain, Canada and New Zealand.

"It is imperative that the international community devise appropriate measures to address current and emerging threats," Rudd said.

Australia has also set up a Cyber Security Operations Centre within the Defence Department, and a new agency, the Computer Emergency Response team, to co-ordinate cyber defences, including threats to private business.

Opening the new agency, Attorney-General Robert McClelland said the rise and increasing sophistication of the cyber threat had been demonstrated by the Stuxnet worm, which changed code in systems controlling critical infrastructure.

Once the code was installed, hackers could remotely control vital systems.

"We've been lucky in Australia to have not been impacted by Stuxnet, but this doesn't mean that we're immune by any means." McClelland said.

"These attacks - while not on home soil - are real, and the threat to critical infrastructure such as banking, telecommunications and government systems is not something we can be complacent about."