The team were "horrified" at the information left in insecure bags

BBC investigators found customer names, addresses and account details when rifling through discarded trash.

The team, from BBC One's Watchdog, say the information could be used by criminals to steal clients' identities.

The information commissioner, Richard Thomas, said he would look into the findings, the team said.

As part of the investigation, to be screened on Tuesday, researchers collected bags of unsecured rubbish left outside banks and building societies in five UK towns and cities.

Among their finds were details of a bank transfer for �500,000 left outside a Nottingham branch of the Royal Bank of Scotland.

Credit cards cut into easily assembled pieces were recovered from outside a Barclays outlet in Bristol.

Horrified

Other discoveries among the trash were customer names, phone numbers, sort codes and account numbers at a Halifax branch in Manchester.

And bank statement details were found outside the Scarborough Building Society in York.

Following the investigation, the information commissioner Richard Thomas is launching a probe, the programme says.

Watchdog editor Rob Unworthy said: "We are horrified at how easy it was to get hold of customers' personal details - and about what could have happened if that information had fallen into the wrong hands."

Separate findings show the ease with which identity thieves can operate.

Nearly half of household rubbish bins contain all the information a fraudster needs to steal a person's identity, a survey by document shredder manufacturer Fellowes found.