BEIJING (AFP) - A Pentagon report accusing Chinese hackers of accessing US weapon designs contained "misjudgements", a spokesman for Beijing's defence ministry said on Thursday, adding that China could build weapons on its own.

US officials, confirming a Washington Post report, had said the breaches were part of a large-scale cyber spying campaign against top US defence contractors and government agencies.

In a statement posted on the defence ministry website, spokesman Geng Yansheng said: "There are misjudgements in the US claims."

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

"China is fully capable of building the weapons and equipment needed to defend national security."

Mr Geng cited as examples the country's new aircraft carrier, fighter jets, transport aircraft and its satellite navigation system.

US officials are increasingly worried about digital spying from China, and the White House said the issue would be high on the agenda when Chinese President Xi Jinping meets President Barack Obama next week.

The Pentagon document cited by the Washington Post said a senior advisory group had concluded that hackers had accessed secret designs for two dozen major weapons systems crucial to missile defences, combat aircraft and naval ships.

The cyber attacks gave China access to advanced technology and could hurt the US military's advantage in the event of a conflict, said the group, called the Defence Science Board.

The document stopped short of accusing Beijing of stealing the designs.

The revelations came shortly after a report that Chinese hackers had stolen top-secret blueprints of Australia's new intelligence agency headquarters.