Payment card giant Visa has confirmed that technical problems hit transaction processing across Europe on Friday.
A Visa spokesperson said the problems had been resolved in the UK and were understood to be resolved Europe-wide, but the cause was not yet known.
The payment card giant said: "We were experiencing some technical problems in our card transaction processing. In some cases this was resulting in card transactions being declined.
"Immediate action was being taken to overcome this problem and we are pleased to confirm that a full service has now been resumed."
Visa apologised to cardholders who experienced difficulties.
Around 4,500 member banks have collectively issued more than 315 million Visa cards across Europe. Visa cards were used to make payments and cash withdrawals worth more than £811 billion in the year to June 2006.
The payments company is currently developing contactless ‘wave and pay’ cards, which are expected to be rolled out across the UK this year. The contactless cards will allow people to pay for transactions worth less than £10 by waving a debit card over a reader, without having to sign a receipt or enter a PIN number.