In this interview with The Guardian, Sergey Brin -- one of Google's co-founders -- warns about the demise of the Internet's freedom as we know it. With the growth of restrictive walled gardens environments (like Facebook and Apple), the entertainment's industry attempts to crack down on piracy and the desire of goverment to control it, the principles of openness and universal access are under greater threat than ever.

He said he was most concerned by the efforts of countries such as China, Saudi Arabia and Iran to censor and restrict use of the internet, but warned that the rise of Facebook and Apple, which have their own proprietary platforms and control access to their users, risked stifling innovation and balkanising the web.

"There's a lot to be lost," he said. "For example, all the information in apps -- that data is not crawlable by web crawlers. You can't search it."

Brin's criticism of Facebook is likely to be controversial, with the social network approaching an estimated $100bn (£64bn) flotation. Google's upstart rival has seen explosive growth: it has signed up half of Americans with computer access and more than 800 million members worldwide.

Brin said he and co-founder Larry Page would not have been able to create Google if the internet was dominated by Facebook. "You have to play by their rules, which are really restrictive," he said. "The kind of environment that we developed Google in, the reason that we were able to develop a search engine, is the web was so open. Once you get too many rules, that will stifle innovation."

He criticised Facebook for not making it easy for users to switch their data to other services. "Facebook has been sucking down Gmail contacts for many years," he said.