China says it was targeted in 500,000 cyberattacks last year, with the majority originating from foreign countries.
A Chinese monitoring agency (National Computer Network Emergency Response Coordination Center) says most of the attacks came in the form of Trojan horse software that installs itself on vulnerable computers.
According to the report, 15 percent of the attacks were traced to IP addresses in the United States and eight percent to those in India.
The report comes days after the U.S. computer security firm McAfee said a nation-state was responsible for some five years of cyberattacks targeting over 70 government entities, nonprofit groups and corporations.
Although the company did not name the country, experts said evidence points to China.
Chinese state media said speculation of a Chinese link was "irresponsible."
The same company said in February that hackers based in China had broken into the computer systems of at least five global energy companies to steal details on bidding for oil fields and other sensitive data.
Some information for this report was provided by AP, AFP and Reuters.