Silicon is reporting that a single UK-based online retailer has been identified as the source of a security breach that has resulted in thousands of MasterCard and Visa holders having their credit cards cancelled this week.
At least 4,000 UK MasterCard holders are believed to have now been affected by the breach which occurred after hackers gained access to credit card details via the as-yet-unnamed e-tailer.
It was initially believed 2,000 credit card details had been stolen after silicon.com exclusively revealed that MasterCard advised card issuers to shut down the accounts of the cardholders affected and issue new cards after discovering the breach.
A spokesman for Visa Europe said: "Visa Europe can confirm that it is aware of a suspected data compromise involving a UK-based online merchant. A full investigation is continuing and Visa is working closely with all appropriate organisations to resolve this issue as a matter of urgency."