The UK's Payment Systems Regulator has fined Barclays Bank £10m for failing to supply retailers with full information about the fees attached to different card services.

The watchdog found that Barclays, the UK's biggest card acquirer, did not provide retailers with transaction information required under the Interchange Fee Regulation (IFR).

Barclays' lack of transparency meant retailers weren't fully aware of the fees they were paying so could not effectively compare prices of card services, shop around to find cheaper deals, or negotiate the best deal with Barclays.  

Chris Hemsley, the PSR's managing director, said: "It's vital that retailers and consumers get value for money on payment services - the interchange fee rules are an important part of making sure this happens. Barclays' failure to be transparent with retailers about the fees they pay for card services meant retailers could have been missing out on better deals." 

The PSR's investigation identified that Barclays failed to comply with the IFR for over three years in total, from December 2015 to December 2018. During this time, Barclays processed a third of all card payment transactions in the UK.  

Hemsley added: "Where we see banks failing to comply with the Interchange Fee Regulation, we have powers to intervene to make sure these important rules are followed, so retailers can make informed decisions about the services they use."