U.S. Navy Photo / AP file This image provided by the US Navy shows a modified Standard Missile 2 interceptor is launched in 2008 from the guided-missile cruiser USS Lake Erie during a test. A new report says Chinese hackers have stolen designs for several U.S. weapons systems.

Chinese hackers have gained access to designs of more than two dozen major U.S. weapons systems, a U.S. report said on Monday, as Australian media said Chinese hackers had stolen the blueprints for Australia's new spy headquarters.

Citing a report prepared for the Defense Department by the Defense Science Board, the Washington Post said the compromised U.S. designs included those for combat aircraft and ships, as well as missile defenses vital for Europe, Asia and the Gulf.

Among the weapons listed in the report were the advanced Patriot missile system, the Navy's Aegis ballistic missile defense systems, the F/A-18 fighter jet, the V-22 Osprey, the Black Hawk helicopter and the F-35 Joint Strike Fighter.

The report did not specify the extent or time of the cyber-thefts or indicate if they involved computer networks of the U.S. government, contractors or subcontractors.

But the espionage would give China knowledge that could be exploited in a conflict, such as the ability to knock out communications and corrupting data, the Post said. It also could speed China's development of its defense technology.

In a report to Congress this month, the Pentagon said China was using espionage to modernize its military and its hacking was a serious concern. It said the U.S. government had been the target of hacking that appeared to be "attributable directly to the Chinese government and military."

China dismissed the report as groundless.

China also dismissed as without foundation a February report by the U.S. computer security company Mandiant, which said a secretive Chinese military unit was probably behind a series of hacking attacks targeting the United States that had stolen data from 100 companies.

In Australia, a news report said hackers linked to China stole the floor plans of a A$630 million headquarters for the Australia Security Intelligence Organization, the country's domestic spy agency.

The attack through the computers of a construction contractor exposed not only building layouts, but also the location of communication and computer networks, it said.

Chinese Foreign Ministry spokesman Hong Lei, asked about the Australian report, said China disapproved of hacking.

"China pays high attention to the cyber security issue and is firmly opposed to all forms of hacker attacks," Hong said at a daily briefing.

"Since it is very difficult to find out the origin of hacker attacks, it is very difficult to find out who carried out such attacks," Hong said. "I don't know what the evidence is for media to make such kinds of reports."

Repeating China's position that every country was susceptible to cyber attacks, Hong said nations should make joint efforts towards a secure and open Internet.

Australia security analyst Des Ball told the ABC that such information about the yet to be completed spy headquarters made it vulnerable to cyber attacks.

"You can start constructing your own wiring diagrams, where the linkages are through telephone connections, through wi-fi connections, which rooms are likely to be the ones that are used for sensitive conversations, how to surreptitiously put devices into the walls of those rooms," said Ball.

The building is designed to be part of an electronic intelligence gathering network that includes the United States and Britain. Its construction has been plagued by delays and cost over-runs with some builders blaming late design changes on cyber attacks.

The ABC report said the Chinese hacking was part of a wave of cyber attacks against business and military targets in the close U.S. ally.

It said the hackers also stole confidential information from the Department of Foreign Affairs and Trade, which houses the overseas spy agency, the Australian Secret Intelligence Service, and had targeted companies, including steel-manufacturer Bluescope Steel, and military and civilian communications manufacturer Codan Ltd.

The influential Greens party said the hacking was a "security blunder of epic proportions" and called for an inquiry, but the government did not confirm the breach.

Prime Minister Julia Gillard said the reports were "inaccurate", but declined to say how.

Despite being one of Beijing's major trade partners, Australia is seen by China as the southern fulcrum of a U.S. military pivot to the Asia-Pacific. In 2011, it agreed to host thousands of U.S. Marines in near-permanent rotation.

Chinese telecommunications giant Huawei was last year barred from bidding for construction contracts on a new Australian high-speed broadband network amid fears of cyber espionage.

The Reserve Bank of Australia said in March that it had been targeted by cyber attacks, but no data had been lost or systems compromised amid reports the hackers had tried to access intelligence negotiations among a Group of 20 wealthy nations.

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