Internet Defense League projects a cat signal on the Bay Bridge in San Francisco to highlight the campaign against Stop Online Piracy Act (SOPA) and Protect Intellectual Property Act.

Washington - The Internet's “superheroes” are rallying to defend online freedom, while taking a page from Hollywood's playbook.

The launch of the Internet Defence League coincides with the US release of the new Batman film The Dark Knight Rises, and will use a bat - er, cat signal - to highlight the campaign.

“While member sites broadcast the news online, we blast our 'cat signal' into the sky with crowd-funded spotlights in cities around the world (on Batman's opening night!),” says the league's web page.

The league, which aims to crush attacks on online freedom anywhere in the world, has several dozen participating organisations, including the Mozilla Foundation, Computer & Communications Industry Association and Electronic Frontier Foundation.

“The goal of the IDL is to sound the alarm quickly to millions of users, through what people are calling the IDL 'a bat-signal for the Internet,'“ according to the New America Foundation, a Washington think tank.

Launch events were planned in San Francisco, New York, Washington, London and Ulan Bator. - Sapa-AFP