The Information Commissioner is investigating claims that two branches of NatWest bank dumped customers' details in outside dustbins.
Campaign group Scamsdirect said it had lodged a complaint after allegedly finding cut-up credit and debit cards and other account information.
The bags were found near the bank's Fareham and Southampton branches.
A spokesman for the Information Commissioner's Office said it had begun an investigation into the claims.
"Clearly, where personal information is not disposed of securely, there is a risk that it will fall into the wrong hands," said the spokesman.
"It is not enough for them merely to have security procedures in place. They must make sure that those procedures are followed in practice."
Commissioner's powers
If the claims are substantiated, the Commissioner has the power to enforce procedures to ensure the same mistake is not made again.
NatWest acknowledged it had been contacted by the Information Commissioner.
"The bags removed by Scamsdirect from our Fareham branch were general waste bags taken from our dustbins outside the branch, " he said.
"Subsequently, we have been made aware that Scamsdirect claim to have found other small amounts of confidential material within general waste at other branches and we are in the process of investigating their claims."
Earlier this month government figures were published which suggested that more than 100,000 people are affected by identity theft each year.
Bank customers - and details of their accounts - are a favourite target for the fraudsters.
^ Back to top | BBC Sport Home | BBC Homepage | Contact us | Help | ©