The British retailer Dixons Carphone says it has discovered a data breach that targeted the card details of millions of customers.

According to the retailer, there was an 'attempt' to compromise 5.9 million cards in a system used by Currys / PC World and Dixons Travel stores.

5.8 million of the cards have chip and PIN protection - and no data related to PIN codes or CCV numbers was accessed.

However, the company says around 105,000 non-EU cards did not have chip and PIN protection, and 'have been compromised'.

Police and data protection authorities in the UK have been informed of the situation, and Dixons Carphone says it has also contacted financial institutions.

The investigation also discovered that 1.2m records containing non-financial personal data - including data such as name, address and email address details - had been accessed.

"We have no evidence that this information has left our systems or has resulted in any fraud at this stage," the retailer suggested.

It was not immediately clear if any Irish customers were impacted, but Carphone Ireland said on Twitter that any affected customers would be contacted.

Dixons Carphone Chief Executive, Alex Baldock, said: "We are extremely disappointed and sorry for any upset this may cause. The protection of our data has to be at the heart of our business, and we’ve fallen short here.

"We’ve taken action to close off this unauthorised access and though we have currently no evidence of fraud as a result of these incidents, we are taking this extremely seriously. We are determined to put this right and are taking steps to do so; we promptly launched an investigation, engaged leading cyber security experts, added extra security measures to our systems and will be communicating directly with those affected."

Dixons Carphone came into existence after the owners of the Dixons / PC World stores merged with Carphone Warehouse in 2014.