Amnesty International has slammed Google, Yahoo and Microsoft for undermining the freedom of the Chinese people by agreeing to Chinese government's demands for censorship.

"All three companies have, in one way or another, facilitated or colluded in the practice of censorship in China," Amnesty said in the report, called "Undermining freedom of expression in China" [pdf]. The report also notes that their actions contradict the companies' own stated values.

This is not the first time that Amnesty has criticised the business practices of the Net giants. Yahoo was widely criticised for handing over user information that helped Chinese authorities identify and jail dissidents, including Shi Tao, a journalist imprisoned in 2005 for 10 years.

Microsoft and Google have also faced criticism from human rights group. Microsoft shut down a blog on its MSN Spaces Web site following a request from the Chinese government and Google introduced a censored version of its search engine specifically designed for China.

All three have defended their business practices, saying they must follow local laws.

Amnesty applauded Google's admission that its actions in China were at odds with its stated corporate mantra of "don't be evil", saying this was a first step. Google can go further by being more transparent about its censorship of search results in China, it said.

Yahoo, which has since handed over its Chinese operations to Alibaba.com, was singled out for the harshest criticism. "Yahoo actions have, in particular, assisted the suppression of dissent with severe consequences for those affected," the report said.

Amnesty called on all three companies to take several measures, aimed at ensuring better freedom of expression in China, including making public all agreements with the Chinese government that related to the censorship of information and to make public the list of words that are censored by content filters.