Visa has emailed an apology to tens of millions of European customers after its online authorisation system suffered a system failure on Friday morning.
Thousands of online Visa card transactions may have gone unprocessed after the system failed at 5.10am. Customers who tried to make transactions saw the error code: '6: Bank Did Not Reply'.
Visa's backup measures in the UK enabled the system to recover three hours after it failed. The company is now carrying out diagnostics.
The credit card giant told customers in an email: "During this [system failure] time period, authorisation requests on some Visa branded cards did not receive any bank response."
Visa admitted that some transactions would not have been processed, but could not say how many. The company said that backup measures had enabled the system to recover.
Europe's 315 million Visa debit, credit and commercial cards were used to make purchases and cash withdrawals of more than £8.1bn in 2006.
Dubbed Barnard's star B, newly discovered planet is believed to be rocky
Also, what's a USB stick?
Gravitational waves become extremely weak by the time they reach the Earth and require highly sensitive equipment for detection
The reactor topped out at 100 million° C