A Foreign Ministry spokesman said Beijing had made "representations" to the US Government over the report, which it described as "not conducive to mutual trust or co-operation".
Colonel Wang Xinjun, a People's Liberation Army researcher, said the accusations were "irresponsible and harmful to the mutual trust between the sides", the official Xinhua News Agency reported.
Colonel Wang, who is based at the Academy of Military Sciences in Beijing, one of the army's main think-tanks, added: "The Chinese Government and armed forces have never sanctioned hacking activities." The military frequently uses such academics as proxy spokesmen.
The decision to turn up the diplomatic heat on Beijing over its use of cyber espionage represents a change of tactics in Washington, where diplomats say that for years they have made behind-the-scenes diplomatic representations to China over the issue.
"We either get flat denials or they shrug, as if to say all governments are involved in this kind of thing, so live with it," said one senior diplomat.
The Obama Administration has signalled its determination to bolster America's defences against cyber spying and attack, asking Congress for a 21 per cent increase in Pentagon cyber security budgets this year.
"What concerns me is the extent to which China's military modernisation occurs in the absence of the type of openness and transparency that others are certainly asking of China," said David Helvey, deputy assistant secretary of defence for East Asia.T