BEIJING - Chinese state media stepped up the war of words Thursday over allegations of sophisticated cyberattacks on US firms, branding the accusations a "commercial stunt" and accusing Washington of ulterior motives.

American Internet security firm Mandiant earlier this week said that a Chinese military cyberspy unit had been targeting US and other foreign firms and organisations with hacking attacks.

But an editorial in the state-run China Daily said: "One cannot help but ask the real purpose of such a hullabaloo.

"With the US economic recovery dragging its feet, it is reasonable to think that some in Washington may want to make China a scapegoat so that public attention is diverted away from the country's economic woes."

Defence ministry spokesman Geng Yansheng said the People's Liberation Army had itself been the target of a "significant number" of cyberattacks.

"A considerable number" of them originated in the United States, judging from the IP addresses involved, he said, but added that he did not accuse the US government of being involved. He had earlier said Mandiant's claims had "no factual basis."

The media backlash came after the US government Wednesday vowed to aggressively combat a rise in the foreign theft of trade secrets.

A new strategy document released by the White House did not explicitly name China, but warned that foreign governments and firms had stepped up efforts to obtain such material, threatening US economic and national security.

In its report, Mandiant alleged the hacking group "APT1" - from the initials "Advanced Persistent Threat" - was part of the Chinese military's Unit 61398 and had stolen hundreds of terabytes of data from at least 141 organisations across 20 industries.

Targeted companies included some involved with significant sections of the American domestic infrastructure.

Western analysts dismissed the Chinese denials as "meaningless."

Photos: Inside China's secretive hacking unit

Hackers hit Apple in wake of Facebook attack

Security group suspects Chinese military is behind hacking attacks

China says US hacking accusations lack technical proof