Charities that refurbish old PCs for people in cash-strapped countries were quick to reassure donors today following a BBC report about sensitive information found on machines sold in markets in the developing world.

The Five Live report, previewing a special investigation to be screened tonight on BBC One's Real Story (7.30pm), found hard disks containing personal data, and even banking details.

But Computer Aid and Digital Links International (DLI) both said they wipe hard disks as part of their refurbishment process.

A DLI statement said it provided a data-destruction certificate to all donors.

Chief executive David Sogan said: "We work in partnership with professional refurbishment companies to ensure absolute security and environmental excellence for our donors."

The problem of sensitive information on hard disks is not restricted to poor countries and a company called Nova Development recently released a utility that cleans old data out of PCs. Simply deleting files is not effective as they can usually be retrieved.