Human rights advocacy group Amnesty International is calling internet search giants out on their weak policy toward the Chinese market.

Microsoft, Google, and Yahoo have all bowed to pressure from the Chinese government to censor internet sites.

Amnesty's report says, "All three companies have demonstrated a disregard for their own internally driven and proclaimed policies".

"They have made promises…which they failed to uphold in the face of business opportunities and pressure from the Chinese government."

Harsher words were still to come: "This raises doubts about which statements made by these organizations can be trusted and which ones are public relations gestures".

Amnesty, in its report entitled "Undermining Freedom of Expression in China", accuses the three companies of violate Article 19 of the Universal Declaration of Human Rights, which says everyone should be guaranteed freedom of expression.

Yahoo.cn filters Chinese search results as requested by the Chinese government, and apparently was partly responsible for the arrest of at least two dissidents after the company supposedly handed over information to the state.

Yahoo said to Reuters that its presence in China could "help open up the country" and that it was also "concerned by the issue".

Google, meanwhile, has also agreed to block "politically sensitive terms" on its Chinese site, but has taken steps, like refusing to offer Gmail in the country, to reduce its involvement in the country.

Google's response to questions from Cnet News.com about its actions in the Chinese market were much the same as Yahoo's: "Google believes that Google.cn will provide significant benefits to Chinese Internet users and that our engagement in China meaningfully expands access to information".