Amnesty International has come out with a report about censorship in China that details how Yahoo!, Microsoft and Google have collaborated with Chinese censors in violation of their own values and policies.

The companies have come under fire recently for bowing to pressure from Chinese authorities to filter out politically sensitive content. As a result, they face potential restrictions on how they behave abroad with a bill pending in the U.S. House of Representatives.

Amnesty International is asking companies to exhaust judicial measures before complying with requests that could impact human rights, such as giving out information about email users. It urges companies to call for the release of dissidents jailed for expressing opinions online. AI also created a Website designed to undermine censorship by spreading the news about censored content on individual blogs and Web sites around the world.