Images of Guy Fawkes masks also appeared with a message on the Chinese websites targeted by  Anonymous hackers.

Story highlights

China acknowledges hacker attack on Chinese websites

Anonymous China claimed to have defaced almost 500 sites

Message referred to Beijing's "evil regime" and warned readers to be "careful"

Follows China's temporary suspension of comments on microblogs

Hong Kong CNN  — 

China has acknowledged that a number of its websites have fallen victim to attack by hackers following a mass campaign by the Anonymous network.

Hackers belonging to the global band of online activists this week claimed to have compromised almost 500 sites belonging to the Chinese government, organizations and businesses.

The cyber attackers plastered the sites with subversive messages, condemning what they described as Beijing’s “evil regime” and warning “Your government has been in control of your network and filters harmful things. Careful.”

While official news sites in China made no mention of the hacking claims, the matter was raised at a briefing of China’s Ministry of Foreign Affairs Thursday.

In a three-part answer, spokesman Hong Lei said that “certain reports prove again” that Chinese sites had been hacked.

“First of all, China’s Internet is open to all, users enjoy total freedom online. China has gained 500 million netizens and 300 million bloggers in a very short period of time, which shows the attraction and openness of China’s Internet,” Hong said.

“Secondly, the Chinese government manages the Internet according to law and regulations. Thirdly, certain reports prove again that China is a victim of internet hacker attacks.”

On Friday, searches for comments on hacking yielded re-posts of the MoFA statement: “we have an open, free cyberspace in China.’” One user on the Weibo micro-blogging site posted in response: “Open? How dare you brainwash your people that?”

The mass attack comes less than a week after the country suspended comments on China’s most popular micro-blogging sites, Sina’s Weibo and Tencent’s QQ.

The two-day suspension was necessary to “clean up rumors and other illegal information spread through microbloggings,” according to state-run news service Xinhua.

Authorities also closed 16 websites and detained six people for allegedly spreading rumors of “military vehicles entering Beijing and something wrong going on in Beijing,” a spokesperson for the State Internet Information Office told Xinhua.

China’s internet was rife with rumors last month of an alleged coup attempt after the shock dismissal Communist Party politburo member and Chongqing party chief Bo Xilai. Cyberspace discussions on Bo’s fate have since been censored.

News of the Anonymous attack in China was spread on Twitter through @AnonymousChina, a relatively new account with less than 3,000 followers at the time of writing. Its first tweet was posted on March 30 and linked to a Chinese website with the words “Hacked by Anonymous.”

A list of nearly 500 sites allegedly hacked were posted on pastebin.

Tweets suggested some were targeted more than once, including the CBD site of Chengdu, the capital of the Sichuan province in the country’s south west – @AnonymousChina: “ redefaced lol, your security still suck.”

At the time of writing, no posts had been made on the Twitter feed for some 12 hours.

While Xinhua did not carry news of the alleged Anonymous hackings, it has reported on their activities in the past.

In February, it reported that the group had taken down the websites of the U.S. Central Intelligence Agency (CIA) and Alabama state government.

Soon after that attack, top members of Anonymous and its offshoots were arrested and charged after a wide-ranging investigation that was assisted by a group leader working as a secret government informant. The FBI informant, “Sabu,” was a part of the elite AntiSec hackers.

In recent years, Anonymous has been involved in some of the most high-profile cyberattacks on the Web – hobbling the websites of governments and businesses, hacking into sites to reveal private data and, along the way, getting dubbed cyberterrorists by authorities in the United States and elsewhere.

The network’s motto is “We are Legion,” and it describes itself as “a decentralized network of individuals focused on promoting access to information, free speech, and transparency.”

CNN’s Shao Tian contributed to this report.