Wikipedia will black out the English language version of its website Wednesday to protest anti-piracy legislation under consideration in Congress, the foundation behind the popular community-based online encyclopedia said in a statement Monday night. The website will go dark for 24 hours in an unprecedented move that brings added muscle to a growing base of critics of the legislation. Wikipedia is considered one of the Internet's most popular websites, with millions of visitors daily.

"If passed, this legislation will harm the free and open Internet and bring about new tools for censorship of international websites inside the United States," the Wikimedia foundation said. The Stop Online Piracy Act in the U.S. House of Representatives and the Protect Intellectual Property Act under consideration in the Senate are designed to crack down on sales of pirated U.S. products overseas.

Tech companies such as Google, Facebook, Yahoo, Twitter, eBay, AOL and others have spoken out against the legislation and said it threatens the industry's livelihood. Several online communities such as Reddit, Boing Boing and others have announced plans to go dark in protest as well. Jimmy Wales, the founder of Wikipedia who first announced the move on his Twitter account Monday, said the bills are a threat to the free, open, and secure web.

Wikipedia is also requesting that readers contact members of Congress about the bill during the blackout.

"I am personally asking everyone who cares about freedom and openness on the Internet to contact their Senators and Representative," Wales said. "One of the things we have learned recently during the Arab spring events is that the Internet is a powerfully effective tool for the public to organize and have their voices heard."

Wikipedia will shut down access from midnight Eastern Standard Time on Tuesday night until midnight Wednesday. 

This is the first time Wikipedia's English version has gone dark. Its Italian site came down once briefly in protest to an Internet censorship bill put forward by the Berlusconi government; the bill did not advance.

"Wikipedia is about being open," said Jay Walsh, spokesman for the Wikimedia foundation. "We are not about shutting down and protesting. It's not a muscle that is normally flexed."