Reports of the problems spread on social media after customers' credit cards were declined when they tried to pay for fuel.
The problem appeared to be limited to Tesco's pay-at-pump transactions, which allow customers to pay for petrol without having to go into the shop. Users inputting the correct pin three times found the payment denied and their cards locked. The terminals require users to put their cards into the machine before they fill up their vehicle.
The issue is the latest in a series of problems for the banks' customers. Millions of RBS/Natwest customers found they could not use their cards on Cyber Monday, the first Monday in December and one of the busiest shopping days before Christmas. On 10 December the bank again apologised after customers were unable to withdraw cash or pay for purchases with their debit cards for about three hours.
An RBS spokesman blamed Tesco for yesterday's problems, and confirmed that all the bank's systems were operating normally.
Tesco said: "We are investigating reports of problems affecting some of our pay-at-pump services. We apologise to our customers for any inconvenience caused."
guardian.co.uk © Guardian News and Media Limited 2010
image: © Elliot Brown