Davos (Switzerland) (AFP) - Imagine a world where mosquito-sized robots fly around stealing samples of your DNA. Or where a department store knows from your buying habits that you're pregnant even before your family does.

That is the terrifying dystopian world portrayed by a group of Harvard professors at the World Economic Forum in Davos on Thursday, where the assembled elite heard that the notion of individual privacy is effectively dead.

"Welcome to today. We're already in that world," said Margo Seltzer, a professor in computer science at Harvard University.

"Privacy as we knew it in the past is no longer feasible... How we conventionally think of privacy is dead," she added.