German Consumer Protection Minister Ilse Aigner has launched an attack on the Internet economy, warning that the likes of Google, Microsoft and Apple store vast amounts of personal information on Web users that can be used for financial gain, and can hurt people's chances of getting jobs or bank loans.

German Consumer Affairs Minister Ilse Aigner warned in an interview published on Monday that Internet giants like Google and Microsoft hold extensive amounts of personal data on Web users and said the firms should reveal what they know about people.

Speaking ahead of the opening of Germany's annual CeBIT, the Hanover-based digital industry trade fair starting on Tuesday, Aigner said some IT companies had built up gigantic databases on their customers and that nobody knew how they were using the wealth of names, addresses and pictures at their disposal.

"Sector giants like Facebook, Apple, Google or Microsoft can compile entire personal profiles in the Internet," Aigner told the German daily Suddeutsche Zeitung. "They know what we're interested in, what we buy, where we travel to and who we're friends with. Some consumers become really interesting for businesses as a result, while others may end up blacklisted and have problems finding work."

"Consumers should be given control over their personal data," said Aigner, who as consumer affairs minister is part of Chancellor Angela Merkel's cabinet. "Companies must give all users insight into which personal data is stored and what happens to it. It must be possible to have private data deleted if desired."

Aigner welcomed a suggestion by Interior Minister Thomas de Maiziere that firms should start telling people every year what personal information they have stored about them. "Such a voluntary commitment by companies could be a solution. At the moment it's hard for consumers to find out who knows what about them," said Aigner.