China's military spokesman said on Wednesday that the country's armed forces had never backed any hacking activities, denouncing the US cybersecurity firm Mandiant's report as groundless both in facts and legal basis.

China's laws ban any activities disrupting cyber security and Chinese government always cracks down on cyber crimes, Geng Yansheng, spokesman with Ministry of National Defense, said at a briefing.

Mandiant on Monday released a report which alleged that a secret Chinese military unit in Shanghai was behind years of cyberattacks against US companies.

The spokesman said Mandiant's report was groundless in fact because the report came into the conclusion that the source of attack came from China only with the discovery that attacks were linked to IP addresses based in China.

First, as known to all, it is a common sense and method on the Internet to conduct hacking attacks by peculating IP addresses, the spokesman said, "it happens almost everyday."

Second, there has been no clear and consistent definition on cyberattacks around the world. The report is lack of legal basis to assert cyber espionage only by collecting some routine cyber activities, Geng said.

Third, cyberattack is transnational, anonymous and deceptive with its source often difficult to be identified. Releasing irresponsible information will not help solve problems, he said.