Updated

As Beijing readies itself for the Olympic Games in August, Chinese dissidents living in the U.S. have launched an attack on the country's so-called "Great Firewall," which prohibits its citizens from having full access to the Internet.

Much like China's state-controlled newspapers, radio and television, the Communist Party maintains a tight grip on the Internet, often blocking access to Web sites critical of the government.

Chinese dissident Bill Xia is among a group of U.S.-based computer hackers — or "hacktivists" — who send mass e-mails to Internet users in China that contain software or links to safe Web sites that enable readers to bypass government roadblocks on the Internet.

• Click here to read Jonathan Serrie's blog on taking down China's "Great Firewall."

As distressing as is Beijing's control of information, Xia said that the censorship continues with the help of some of America's largest and best-known technology firms — such as Yahoo, Google and Microsoft.

"United States is based on freedom of expression and other personal freedoms," Xia said. "However, many of those companies actually help with censorship in countries like China. So I think this is outrageous."

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• Click here for foxnews.1eye.us's Personal Technology Center.

Nothing better illustrates this than doing a Google Images search for "Tiananmen Square."

Do it in the U.S. and you get images of the 1989 pro-democracy rally in Beijing and the government's violent military response.

Do the same search in China, however, and it produces tourist photographs of the public square without scenes of civil unrest.

Xia said he fears reprisals from Chinese authorities for his e-mail work, which he said is best accessed in China from public areas, such as Internet cafes, but can also be used from private locations.

He's not the only one who is risking personal safety to get around the censors.

A U.S.-run Web site, Boxun.com , is also providing Chinese citizens with hard-to-get-information.

It reportedly relies on bloggers and citizen journalists mostly in China, instead of state-controlled media or foreign news services, to report stories.

The site, operated by Watson Meng of North Carolina, is banned in China but can be readily accessed by Chinese users via proxy servers hosted in the United States.

Testifying at a Congressional hearing in 2006, Google Vice President Elliot Schrage said that while his company didn't agree with China's restrictions, his and other American firms were forced to abide by Chinese regulations to continue operations in the country.

He said that if they didn't comply, other companies would.

"At the risk of oversimplification, the U.S. should treat censorship as a barrier to trade and raise that issue in appropriate fora," Schrage said.

Executives from Cisco, Microsoft and Yahoo also testified about instances where U.S. companies allegedly provided Chinese authorities with user data on dissidents that led to beatings, arrests and even imprisonment.

Congressman Chris Smith, R-N.J., is proposing legislation that would make such cooperation illegal.

"If you realize that your technology is being used for nefarious purposes, I would hope that you would either want to extricate yourself or buy into this legislation that, at least, makes it possible to do business there, but do so in a principled way," Smith said.

In May, China's technology minister, Wan Gang, told Reuters that China would "guarantee as much [access] as possible" on the Internet while defending the country's Web limitations to protect citizens from illegal and offensive content.

But China's record of cracking down on dissidents doesn't bode well, especially with the approaching Olympic Games.

"Because of the human-rights violation in China, we should put moral consideration to high priority," Smith said.

David Lewkowict and Josh Miller contributed to this report.