BEIJING — Google's accusation that its e-mail accounts were hacked from China landed like a bombshell because it cast light on a problem that few companies will discuss: the pervasive threat from China-based cyberattacks.
The hacking that angered Google Inc. and hit dozens of other businesses adds to growing concern that China is a center for a global explosion of Internet crimes, part of a rash of attacks aimed at a wide array of targets, from a British military contractor to banks and chemical companies to a California software maker.
The government denies it is involved, and it reiterated that on Wednesday. Speaking in Paris, China's foreign minister, Yang Jiechi, said China itself "is the victim of pirate attacks" and the international community must fight the phenomenon together.
But experts say the highly skilled attacks suggest the Chinese military, which is a leader in cyberwarfare research, or other government agencies might be breaking into computers to steal technology and trade secrets to help state companies.
"Chinese hacking activity is significant in quantity and quality," said Sami Saydjari, president of the consulting firm Cyber Defense Agency and a former U.S. National Security Agency official.
Officials in the United States, Germany and Britain say hackers linked to China's military have broken into government and defense systems. But attacks on commercial systems receive less attention because victims rarely come forward, possibly for fear it might erode trust in their businesses.
Google was the exception when it announced Jan. 12 that attacks hit it and at least 20 other companies. Google says it has "conclusive evidence" the attacks came from China but declined to say whether the government was involved.
Only two other companies have disclosed they were targets in that attack — software maker Adobe Systems Inc. and Rackspace Inc., a Web hosting service.