US Defense Secretary Chuck Hagel on Saturday accused China of waging cyber espionage against the United States, raising pressure on Beijing over the issue ahead of a key summit between their leaders.

The Pentagon chief, speaking at a Singapore security forum attended by senior Chinese military officials, pointedly blamed the Chinese government and armed forces for repeated intrusions into sensitive US information systems.

"The United States has expressed our concerns about the growing threat of cyber intrusions, some of which appear to be tied to the Chinese government and military," he told an annual conference known as the Shangri-La Dialogue.

Hagel pressed Beijing to adhere to "international norms of responsible behaviour in cyberspace", while acknowledging that the establishment of a joint cyber security working group was a positive step in fostering dialogue.

The Singapore conference took place ahead of the June 7-8 meeting between US President Barack Obama and his Chinese counterpart Xi Jinping in California, the first meeting between the two leaders since Xi took office in March.

Hagel's remarks came just days after China's defence ministry dismissed a Pentagon report accusing Chinese hackers of accessing US weapons designs.

"First they underestimate the security defence capabilities of the Pentagon and second they underestimate the intelligence of the Chinese people," it said.

The report was the most explicit statement yet from Washington that it believes China's cyber spying is focused on the US government and corporations.

In his speech, Hagel insisted that Washington's military "rebalance" towards Asia-Pacific -- a policy announced at the forum last year by his predecessor Leon Panetta -- will not be affected by cuts in US military spending.

He said the US Air Force had allocated 60 percent of its overseas-based forces to the region including tactical aircraft and bombers.

Hagel added that 2,500 US Marines will eventually be deployed to Australia each year as part of the effort.

Last year, Washington announced a major naval deployment to Asia, including the rotation of up to four Littoral Combat Ships -- newly developed vessels designed for coastal operations -- to Singapore, a staunch US supporter.

Hagel said Washington remained concerned "over the potential for dangerous miscalculations or crises" arising from competing territorial claims in Asia.

Other defence officials warned the forum against an arms race in Asia, where governments, boosted by stronger economic growth and worried by regional tensions, are modernising their armed forces.

"In order to avoid military modernisation becoming destabilising, there is a need for greater strategic transparency," Indonesian Defence Minister Purnomo Yusgiantoro said.

Hagel announced that he was inviting his counterparts from the 10-member Association of Southeast Asian Nations (ASEAN) to Hawaii next year, which would be the first such meeting hosted by the United States.

Four of ASEAN's 10 member states -- Brunei, Malaysia, the Philippines and Vietnam -- are locked in territorial disputes with China.

But smaller ASEAN member countries like Laos and Cambodia appear to have come under increasing Chinese economic and political influence, partly as a result of foreign aid from Beijing.

Hagel also used the conference to reaffirm Washington's defence treaty with its former colony the Philippines, which has been the most vocal opponent of Chinese territorial ambitions in the South China Sea.

The Philippines and the United States, whose soldiers fought side by side in the Pacific theatre during World War II, are bound to help defend each other in case of external attacks under a mutual defence treaty signed in 1951.

Australia spy chief says new building safe
Sydney (AFP) May 31, 2013 - Australia's spy chief has declared the nation's new intelligence headquarters secure after reports Chinese hackers stole the building's top secret blueprints.

Speaking for the first time since the reports aired Monday, Australian Security Intelligence Organisation (ASIO) director general David Irvine said security would meet "very, very high standards".

Irvine would not confirm or deny whether Chinese hackers had obtained the floor plan and cable layouts for the security and communications system of the Canberra building.

"We incur all sorts of risks if intelligence operation matters are aired in public," he told a parliamentary hearing late Thursday.

"Can I just assure you though, that I am satisfied that the security of the ASIO building is, and will be, meeting the very, very high standards that are required of a building of that nature."

The Australian Broadcasting Corporation reported on a cyber attack on a contractor linked to the new Canberra headquarters of ASIO which it said was traced to a server in China.

Beijing has said it was "very difficult to find the origin of hacker attacks", with foreign ministry spokesman Hong Lei questioning "where the evidence is for the relevant media to make such reports".

The news came as a Pentagon report also accused Chinese hackers of accessing US weapons designs as part of a large-scale cyber spying campaign against top US defence contractors and government agencies.

China described these as "misjudgements".

In his comments, Irvine said ASIO had also reviewed the terror threat to Australia following the hacking to death of a British soldier in London but concluded it should remain at medium -- a level indicating an attack is feasible and could occur.

"Some sort of crippling fear of a terrorist attack should not dominate the way Australians live their lives," he said.

"Nevertheless we should all... continue to be alert to the fact that there... will be a small number of people within our midst who still talk and some aspire to walk the language of terrorism."

Irvine said the "threat from home-grown lone actor terrorists, or small localised groups who are often largely self-radicalised and see it as some sort of religious or political obligation to conduct an attack" remained.