The London-based human rights group also called on the Internet companies to publicly oppose Chinese government requests that violate human rights standards.
The companies "have violated their stated corporate values and policies" in their pursuit of China's booming Internet market, the statement said. It appealed to them to "call for the release of `cyber-dissidents."'
Spokespeople for Yahoo Inc., Microsoft Corp. and Google Inc. didn't immediately respond to requests for comment. In the past, the companies have defended their actions, saying they are obligated to obey Chinese law and that the Chinese public benefits from access to their services.
China has the world's second-largest population of Internet users after the United States, with 123 million people online. Though the communist government promotes Internet use, it has also set up an extensive surveillance and filtering system to prevent Chinese from accessing material considered obscene or politically subversive.
The Amnesty statement appealed to Internet companies to reveal details of their dealings with Chinese authorities and to exhaust all judicial appeals before complying with government requests that might affect human rights, such as the release of e-mail account information, according to the AP.
A growing number of Chinese journalists and others have been jailed for posting politically oriented comments online and other Internet-related activities.
Yahoo has been the most severely criticized after the Sunnyvale, California-based company's China operation provided information on e-mail users that was used to sentence two dissidents to prison. Yahoo China is operated by Yahoo's local partner, Alibaba.com.
Google has been criticized for censoring search results on its China site. Microsoft has banned terms such as "human rights" from its Chinese Web log service and shut down the U.S.-based log of a Chinese blogger at Beijing's request.
After it turned out that Deputy Prime Minister Andrei Belousov included the Fonbet betting company in the list of backbone enterprises that can count on state support, everyone started talking about these bookmakers.