Shares in Dixons Carphone fell more than five per cent this morning after it announced the launch of an investigation finding there had been "unauthorised access to certain data" held by the company.
The attack involved the processing systems of Currys PC World and Dixons Travel stores, the electronics retailer said Wednesday in a statement, adding that there was no evidence of any fraudulent use of the data at this stage.
It said there was now no evidence of any fraudulent use of the information - with the vast majority of the cards having chip and pin protection.
The retailer said 5.8 million of the payment cards targeted were protected by chip and Pin, but that around 105,000 non-EU cards without chip and Pin protection were compromised.
Dixons Carphone chief executive Alex Baldock admitted the group had "fallen short" of its responsibility to protect customer data. "The protection of our data has to be at the heart of our business, and we've fallen short here", he added.
"We have taken action to close off this access and have no evidence it is continuing", the company said.
Murder probe as hunt under way for killers of Polish man The scene where the vehicle was found and the house where the attack took place have been sealed off for forensic examination. A auto , believed to be a BMW 3 Series, was later found burned out six kilometres away at Iniskenny, Ballinora, Waterfall.
Last month, the retailer forecast that earnings this year will slump about 21 percent as it closes mobile-phone stores in a contracting United Kingdom household-electronics market.
Some security experts said that the leaked personal information was arguably a greater threat than the compromised card data.
Pretax profit will drop to about 300 million pounds in the year ending April 2019, Dixons Carphone said.
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"The fact this only came to light now thanks to a review of the company's systems and data and actually occurred in 2017 is also cause for some concern", he said.
Others compared the Dixons Carphone breach to the compromise of United States retailer Target in arguing lessons have not been learned. Baldock added that Dixons Carphone has also "added extra security measures" to its systems.
'We are contacting those whose non-financial personal data was accessed to inform them, to apologise, and to give them advice on any protective steps they should take.