Amnesty International is accusing Internet companies of violating the Universal Declaration of Human Rights by working with Chinese government censors. The human-rights group also warns that technology now being used to censor the Internet in China could be exported abroad.

Amnesty singled out Internet companies Google, Microsoft and Yahoo for criticism, accusing all three of violating human rights and their own corporate standards by working with Chinese censors. Amnesty spokesman Mark Allison says China is considered to have the world's most advanced Internet controls and its censorship tactics could spread.

"Our concern is the type of censorship happening in China could quite easily be exported to other countries as well, particularly if China becomes more politically and economically powerful," he said.

Amnesty has urged the companies to publicly resist government censorship efforts and to lobby for the release of imprisoned cyber-dissidents. Allison says companies should be more open about their business practices in China.

"Companies should also be making publicly available all of the agreements that they have signed with the Chinese government that have implications for censorship of information," he said.

Rights groups have accused Yahoo of providing officials with information about Chinese journalist Shi Tao that led to his arrest and 10-year prison sentence. Microsoft has banned some words from its Chinese Web log sites. The popular Web search company Google has been criticized for offering a search engine in China that blocks Web sites opposed by government censors.

The companies defend such practices by arguing that Chinese users ultimately benefit from access to their services even if that access is limited.

But Amnesty's Allison says they must do more.

"A lot of these companies have very principled statements on human rights as part of their wider operations," he said. "We want to see those companies putting those statements into practice in terms of their day- to-day operations and investments in certain countries."

As part of its campaign against Internet repression, Amnesty is promoting its "irrepressible-dot-info" Web site. The site publishes examples of censored Internet content and encourages Web page owners to copy the banned content onto their own Web sites in a grass-roots effort to thwart government censors.