If you're planning on getting rid of an old computer, make sure you remove the hard drive first and smash it up with a hammer, a British consumer group advised today.

Which? Computing magazine said the only way to make sure fraudsters could not steal personal details from an old computer's hard drive was to utterly destroy it, as simply deleting files or wiping the drive was not sufficient.

Which? said it had bought eight second-hand drives from Internet auction site eBay and recovered 22,000 "deleted" files, including some information that could be confidential.

Criminals, who it said trawled council waste sites and internet sites like eBay, would be able use specialist software to retrieve the information which could then be used to commit identity theft.

"PCs contain more valuable personal information than ever as people increasingly shop online, use social networking sites and take digital photos," said Sarah Kidner, Editor of Which? Computing.

"Even if you delete your files, you'd be surprised how easy it is to recover your personal data. It sounds extreme, but the only way to be 100 percent safe is to smash your hard drive into smithereens."