Lawmakers on Wednesday accused U.S.-based Internet companies of giving in to pressure from China and helping to censor Web users in violation of American principles of free speech.

They also criticized the four companies -- Microsoft Corp., Yahoo! Inc., Cisco Systems Inc. and Google Inc. -- for failing to attend a congressional briefing that was staged to bring to light how Internet companies do business in China.

Microsoft and Yahoo! issued a joint statement made available saying that, by themselves, they lack the leverage to influence world governments. The statement suggested the four companies could work together with governments to better protect the interests of all Internet services.

Rep. Tom Lantos, D-Calif., co-chairman of the Congressional Human Rights Caucus, said, "There has been a string of disturbing incidents in which U.S.-based Internet companies have bowed to pressure from Beijing."

He said that instead of using their considerable resources to develop new technologies to bypass government gatekeepers, the Internet companies have agreed to guard the gates themselves.

Google provoked criticism last week by launching a new search engine in China that will censor some results to comply with the country's free-speech restrictions.

Reporters Without Borders, an advocacy group, said it had proved that Yahoo! helped the Chinese police identify and convict Shi Tao, a journalist who criticized human rights abuses in China.

Lantos, top Democrat on the House International Relations Committee, said: "These massively successful high-tech companies, which couldn't bring themselves to send representatives to this meeting today, should be ashamed. They caved in to Beijing for the sake of profits."

Rep. Tim Ryan, D-Ohio, said American companies will continue to expand in the Chinese market, "but they should not let profits take precedence over traditional democratic values such as freedom of speech."

Although Beijing has supported Internet use for education and business, it fiercely polices content. Filters block objectionable foreign Web sites, and regulations ban what the Chinese consider subversive and pornographic content and require service providers to enforce censorship.

Foreign companies have adopted Chinese standards, saying they must obey local laws.

In their statement, Microsoft and Yahoo! said they wanted to assure lawmakers and the public "that we do not consider the Internet situation in China to be one of `business as usual."'

Carolyn Bartholomew, acting chairwoman of the U.S.-China Economic and Security Review, a congressionally mandated monitoring group, said China has begun to assume the role of technological leader among the developing nations in its region.

"China serves as the regional Internet provider for surrounding oppressive regimes, including North Korea and Uzbekistan," she said. "Through this role as Internet gatekeeper China exports its filtering technologies to other governments that may choose to employ them."

While attendance at Wednesday's briefing was not mandatory, companies could be compelled with subpoenas to attend a Feb. 15 hearing on the issue, said Rep. Chris Smith, R-N.J., chairman of the House International Relations subcommittee on global human rights.

In an interview, the lawmaker criticized U.S. Internet companies, saying they were helping China arrest and torture activists and screen information from its citizens.

"This is not benign or neutral," Smith said of companies acceding to China's demands. "They have an obligation not to be promoting dictatorship."

Microsoft, Cisco and Google said they planned to attend the Feb. 15 hearing. Yahoo! didn't respond to messages left by The Associated Press.