The four companies have been accused of putting profits before principles in their push to win market share in China.

In a briefing by the U.S. Congressional Human Rights Caucus, the companies were condemned for allowing profits to precede democratic values such as freedom of speech.

All four companies have been summoned to a February 15 hearing by the House International Relations Subcommittee, which oversees human rights issues.

The briefing Wednesday was led by Representative Tim Ryan, who said the censorship involved preventing Chinese citizens from seeing Web sites not supported by the government. Both Google and Microsoft have admitted to engaging in censorship.

Yahoo has allegedly provided online information to the Chinese government which led to a Chinese journalist going to jail.