The UK’s data protection watchdog received more legitimate complaints against Barclays Bank than any of the other major banks or building societies last year, research by consumer rights publisher Which? Money has found.

From August 2009 to August 2010, the Information Commissioner’s Office received 116 complaints about the bank "where compliance with [data protection principles] was assessed as unlikely". Lloyds TSB was just behind with 114 such complaints.

The most frequent complaints related to "subject access requests", when an individual asks an organisation to reveal what data it holds about them. The ICO found that 272 such complaints against the UK’s eight major banks were valid, in that the bank had breached the act by failing to comply with the individual’s request.

The next most frequent cause for complaint was "inaccurate data". The ICO received 41 valid complaints about the accuracy of Barclays’ data during the period in question.

In response to the report, Barclays said it is committed to protecting its customers’ data. "We have no greater priority than the security of our customers’ money and personal information," it said in a statement. “Whenever there is a substantial data breach we ensure we alert the Information Commissioner’s Office, the FSA and our customers where appropriate and we do everything we can to minimise the risk."

The ICO said the numbers reveal serious issues with the way financial institutions handle customer data. "While the number of upheld complaints is small compared to the millions of bank accounts in the UK, mishandling of financial information can have a serious effect on individuals’ lives," it said. "It needs to be looked after properly and customer’s data protection rights respected."

The full investigation is available in the June issue of Which? Money.