Cyber attacks on China launched from bases overseas surged in 2011, rising to 8.9 million computers affected from 5 million in the previous year, according to a network security report.

Japan was the source of most attacks (22.8 percent), followed closely by the United States (20.4 percent) and the Republic of Korea (7.1 percent).

The report, released on March 19 by China's National Computer Network Emergency Response Technical Team and Coordination Center, found that 11,851 Internet protocol addresses based overseas took control of 10,593 Chinese websites last year.

Attacks included destroying servers, distorting website content and stealing personal data from Chinese Web users.

Overseas hackers altered the content of 1,116 Chinese websites, including 404 run by government agencies, said Wang Minghua, deputy director of the center's operation department, at a news conference on March 19.