Sir Tim Berners-Lee, a founder of the Web, criticized social networks and other Internet services claiming they are "a threat to the web." He thinks that Facebook-like websites encourage users to enter their information, which is captured and then reused, but not shared with other websites.

"Large social-networking sites are walling off information posted by their users from the rest of the web," he said in the Scientific American journal.

Singling out Facebook, LinkedIn and Friendster, Berners-Lee added: "Your social-networking site becomes a central platform -- a closed silo of content, and one that does not give you full control over your information in it."

"The more this kind of architecture gains widespread use, the more the web becomes fragmented -- and the less we enjoy a single, universal information space."

He also slammed Apple and iTunes for being "centralized and walled off".

"You can access an iTunes link only using Apple's patented iTunes program," he said.

"You are no longer on the web. You are trapped in a single store, rather than being on the open marketplace. For all the store's wonderful features, its evolution is limited to what one company thinks up."