40 million Target customers details stolen in second ever largest retail breach

Credit card details stolen by hackers in the run up to Christmas

Debit and credit card details of 40 million Target customers might have been stolen by cyber criminals in the run up to Christmas, the US chain store has confirmed.

It represents the second largest data breach at Target - the second largest discount retailer in the United States behind Walmart - and it's believed to have affected all of Target's 1,797 stores US stores.

The breach, first occurred on America's biggest shopping day of the year, Black Friday, which sees stores discounting products and marks the start of "the holiday season" in the United States.

The data theft took place over an almost three week period before being detected on December 15th. The public statement about the theft of 40 million customers details comes four days after it was discovered, but Target has said that once the breach was found it immediately began working with the authorities and financial institutions.

Target customers' details including credit and debit card numbers, full names, expiration dates and security codes have all potentially been stolen, the company has confirmed.

It has warned customers who've purchased items in the run up to Christmas to thoroughly check bank statements for purchases made by hackers using stolen details.

The company has also warned customers its doing everything possible to get to the bottom of the hack.

"Target's first priority is preserving the trust of our guests and we have moved swiftly to address this issue, so guests can shop with confidence. We regret any inconvenience this may cause," said Gregg Steinhafel, chairman, president and CEO of Target.

"We take this matter very seriously and are working with law enforcement to bring those responsible to justice."

The US Secret Service has confirmed it's working alongside Target as it investigates the cause of the breach and attempts to track down the cyber-criminals responsible for it.

With 40 million affected customers, the Target breach isn't far behind the largest ever credit card data breach in the United States when hackers managed to make off with 46 million credit card details belonging to TJ Maxx and Marshalls customers.