WASHINGTON – US Secretary of State Hillary Clinton renewed her call for Internet freedom on Tuesday, saying countries that suppress online activity risk a public backlash like in Egypt and Tunisia.

Clinton, in a speech at George Washington University here, also said the publication of secret US diplomatic cables by WikiLeaks was an "act of theft" and did not clash with the US commitment to an open Internet.

Making her second major speech on Internet freedom in the past year, Clinton said the United States supports the "freedoms of expression, assembly, and association online" and she urged other nations to do the same.

"This is a critical moment," Clinton said. "The choices we make today will determine what the Internet looks like in the future."

She said the United States would continue to help "people in oppressive Internet environments" with censorship circumvention technology.

"Some have criticized us for not pouring funding into a single technology -- but there is no silver bullet in the struggle against Internet repression," she said. "There's no 'app' for that."

"The Internet has become the public space of the 21st century -- the world's town square, classroom, marketplace, coffee house, and nightclub," Clinton said. "We all shape and are shaped by what happens there."

Clinton said protests in Egypt and Iran fueled by Facebook, Twitter and YouTube reflected "the power of connection technologies as an accelerant of political, social, and economic change."

"Consider what happened in Tunisia, where online economic activity was an important part of the country's ties with Europe, while online censorship was on par with China and Iran," she said.

"The effort to divide the economic Internet from the 'everything else' Internet in Tunisia could not be sustained. People, especially young people, found ways to use connection technologies to organize and share grievances.

"This helped fuel a movement that led to revolutionary change."

"Those who clamp down on Internet freedom may be able to hold back the full expression of their people's yearnings for a while, but not forever," she said.

She said efforts to clamp down on the Internet brings "a variety of costs -- moral, political, and economic."

"Countries may be able to absorb these costs for a time, but we believe they're unsustainable in the long run," she said. "When countries curtail Internet freedom, they place limits on their economic future.

"We believe that governments who have erected barriers to Internet freedom... will eventually find themselves boxed in," she said.

"They?ll face a dictator?s dilemma, and have to choose between letting the walls fall or paying the price to keep them standing," Clinton said.

Clinton singled out China, Cuba, Iran, Myanmar, Syria and Vietnam as countries that restrict access to the Internet or arrest bloggers who criticize the government.

"In Iran, the authorities block opposition and media websites, target social media, and steal identifying information about their own people in order to hunt them down," she said.

Clinton also announced plans to launch Twitter feeds in Chinese, Russian and Hindi, just days after starting Twitter feeds in Arabic and Farsi.

On WikiLeaks, Clinton said the US government had no role in the decision by a number of US companies, including Amazon, MasterCard, PayPal and Visa, to cut off services to WikiLeaks following its release of secret US diplomatic cables.

"Any business decisions that private companies may have taken to enforce their own policies regarding Wikileaks was not at the direction or the suggestion of the Obama administration," Clinton said.

The US secretary of state also said "the fact that Wikileaks used the Internet is not the reason we criticized it.

"Wikileaks does not challenge our commitment to Internet freedom," she said.

"Fundamentally, the Wikileaks incident began with an act of theft," she said. "Government documents were stolen, just the same as if they had been smuggled out in a briefcase."

Clinton's speech came on the same day as a US judge was holding a hearing in Virginia into a US government attempt to obtain information about the Twitter accounts of people connected with WikiLeaks.

WikiLeaks founder Julian Assange described the US move on Monday as an "outrageous attack by the Obama administration on the privacy and free speech rights of Twitter's customers -- many of them American citizens."