China's top search engine Baidu was hacked Tuesday in what state media said was an attack by a pro-Iranian government group that replaced the usual home page with an Iranian flag.
Internet users trying to access the site found a message saying "This site has been hacked by Iranian Cyber Army", the People's Daily reported on its website.
Below a sentence in Farsi read, "In reaction to the US authorities' intervention in Iran's internal affairs. This is a warning," the report said, posting an image of the hacked page.
Baidu spokesman Victor Tseng said service was interrupted "due to external manipulation of its DNS (Domain Name Server) in the United States".
"Baidu has been resolving this issue and the majority of services have been restored," the spokesman said in an email to AFP.
The state-run China News Service quoted an unnamed official at Baidu as saying the website's domain name had been hijacked, redirecting traffic to another site, but it is unclear whether those responsible were in fact Iranian.
"The Iranian Cyber Army" was the name used by hackers who briefly shut down the popular microblogging site Twitter last month, using a method similar to that seen in the Baidu strike.
Iranian demonstrators protesting the results of June presidential elections used Twitter extensively, both to organise marches and to release information about their movement.
Their use of the microblogging site led some to dub the pro-democracy action against President Mahmoud Ahmadinejad a "Twitter revolution".
However, the reason for the attack on the Chinese Internet giant was not immediately clear.
Authorities in China blocked Twitter and other Internet social networking sites after the protests in its far-western Xinjiang region last July, fearing such sites could be used to foment unrest as they had in Iran, analysts said.
But Baidu has always remained accessible.
Chinese foreign ministry spokeswoman Jiang Yu condemned any attempt to attack Chinese websites.
"If that was the case, we resolutely oppose hacking and other Internet crimes," Jiang told reporters when asked about the Baidu attack.
Baidu, the nation's biggest search engine, had 63.9 percent of China's search engine market as of the end of September, followed by 31.3 percent for Google China, according to Internet research firm Analysys International.Reuse content