The concept of using web-based programs like Google's Gmail is "worse than stupidity", according to a leading advocate of free software. Cloud computing – where IT power is delivered over the internet as you need it, rather than drawn from a desktop computer – has gained currency in recent years. Large internet and technology companies including Google, Microsoft and Amazon are pushing forward their plans to deliver information and software over the net.

Stallman, who is a staunch privacy advocate, advised users to stay local and stick with their own computers.

"One reason you should not use web applications to do your computing is that you lose control," he said. "It's just as bad as using a proprietary program. Do your own computing on your own computer with your copy of a freedom-respecting program. If you use a proprietary program or somebody else's web server, you're defenceless. You're putty in the hands of whoever developed that software."

Cloud computing is a trap, warns GNU founder Richard Stallman www.stallman.org