Visa and MasterCard accounts hacked

Millions of credit card accounts belonging to Visa and MasterCard customers have been exposed by a hacker who broke into the systems of a third party company which provides processing services to merchants.

Early reports suggest none of the exposed data, which included credit card numbers, has been used fraudulently - though the very fact the breach of security occurred will be a cause of great concern for the companies involved and their customers.

Neither MasterCard nor Visa have been able to provide any indication as to how the attack could have taken place, or what the timescale of the breach was, as it did not involve their systems.

The companies are also remaining tight-lipped about the identity of the third party company providing the transaction processing whose systems were breached.

In total around two million MasterCard accounts were exposed and around 3.4 million Visa accounts.

Both companies say they have contacted all customers, predominantly based in the US, who have been affected by the hack attack.