A popular website of classified ads that has given Cubans a taste of the free market has been blocked on the communist-run island, Internet users said.

Cubans trying to access Revolico.com, which says it has more than 1.5 million page views a month, are being diverted to the search engine Google.com.

If I type the address and press 'enter,' I get redirected. If I Google it and click, I get redirected. What is going on?, asked Sandra a 30-year-old government employee who, like several others interviewed, did not give their full names.

Cuban computer experts say an Internet content filter is preventing access to the Craigslist-like site, which has emerged as a booming virtual free market in the socialist nation with a tightly controlled economy where consumer goods tend to be scarce and expensive.

On Revolico.com, Cubans with access to the Internet can buy and sell anything from computer memory sticks to a 1950 Plymouth.

There you can find all the things the government sells you at brutal prices and freely pick exactly what you want, said Alberto, who recently used Revolico.com to buy a computer that was not available in the stores.

The Internet in Cuba is controlled by the state monopoly ETECSA, a joint venture between the Cuban government and Telecom Italia.

Whether the state was blocking the site was unknown but Cuban authorities have in the past reportedly prohibited access to pages they consider counter-revolutionary, including blogs critical of the socialist system.

Apparently someone doesn't like people buying and selling stuff. But there is always a way, said Luis, a computer aficionado

who has been circulating an e-mail giving directions on how to bypass the filter.

It is not clear where Revolico.com is based but it is hosted out of servers in the United States. An administrator contacted by Reuters outside of Cuba said the site is aware of the filter problem and working to resolve it.

INTERNET FILTERING

The use of content filters is growing around the world, according to The OpenNet Initiative (http://opennet.net), an academic program monitoring online censorship.

We have just finished our testing in 71 countries and have found evidence of content filtering in close to 40 countries, said Ronald Deibert, director of the Citizen Lab at the University of Toronto and co-founder of The OpenNet Initiative.

Countries like China or Iran use filters to prevent access to sites viewed as politically challenging. Some Western democracies say they use them to block websites with child pornography.

Official statistics show that 13 percent of Cuba's 11 million people have access to the Internet and most of those only to e-mail and a local intranet of approved sites. Cuba blames the long-standing U.S. trade embargo against the island for its limited access.

The filters on Revolico.com come after Cuba recently blocked the use of the free call service Skype.com in what industry sources said was a purely commercial decision to keep Skype from cutting into revenues for long-distance calls through the phone system.

Internet service providers in other countries such as China, the United Arab Emirates and even the United States have taken similar steps in the past.

The U.S. trade embargo, imposed since 1962 to undermine the Cuban government, also has caused U.S. companies such as Microsoft Corp and Google Inc to not provide instant messaging services in Cuba because they say U.S. regulations prohibit required downloads.

The Obama administration now is saying it wants the companies to resume the service because they foster communications and democracy.

(Editing by Jeff Franks and Bill Trott)

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