Cutbacks at RBS and NatWest were blamed yesterday for a technical glitch that left customers unable to use their debit and credit cards on Monday.

The embarrassing failure, which left some unable to pay after filling up with petrol or to settle restaurant bills, and in other cases forced them to abandon full shopping trolleys, was the latest in a string of system meltdowns for the RBS-owned group.

It came on so-called Cyber Monday - the day online retailers expected the most sales to take place before Christmas.