Google has said it may pull out of China because it is no longer willing to accept censorship of its search results.
The announcement comes amid growing tensions between China and the US over internet freedoms, with US Secretary of State Hillary Clinton set to announce a technology policy next week to help citizens in other countries gain access to an uncensored web.
Google said it had uncovered a sophisticated attack on the e-mail accounts of Chinese human rights activists using its Gmail service, and that more than 20 other companies were similarly attacked.
'These attacks and the surveillance they have uncovered - combined with the attempts over the past year to further limit free speech on the Web - have led us to conclude that we should review the feasibility of our business operations in China,' Google chief legal officer David Drummond said in a statement posted on the company's blog.
'We recognise that this may well mean having to shut down Google.cn, and potentially our offices in China, he added.
The search market in China, while small in revenue terms, has 360 million internet users and is viewed as a critical battleground for Google. It is one of the rare markets where the US company is not in the lead, lagging homegrown rival Baidu, which commands a 60% share of the Chinese search market, against Google's 30%.
China's tough stance on web censorship has put it at odds with Western technology firms in recent years. In June, Beijing ordered Google to block overseas sites with 'vulgar' content from being accessible through the Chinese language version of its search engine.
Google said then that it met Chinese government officials and was taking necessary steps to ensure search results on its Chinese site complied.
Google said the hackers had tried to access the Gmail e-mail accounts of Chinese human rights activists but managed to access only two unidentified accounts, and then only subject headings and other data such as when the account was created.
It did not say what information the hackers tried to access from the other corporations, nor which they were. Google said it was now notifying the other affected corporations, adding that it was working with the US authorities.
