Last week, Carphone Warehouse suffered a cyber-attack, it has emerged.
The company has admitted that the attack was discovered on Wednesday and made public on Saturday. The personal details of up to 2.4 million of the company's customers may have been accessed – this includes names, addresses, dates of birth and bank details. The encrypted credit card details of up to 90,000 people may also have been compromised.
Customers who have been affected will be contacted, the mobile phone provider said.
The Information Commissioner's Office has confirmed that it is aware of the incident and it is currently "making inquiries," reports the BBC.
According to Carphone Warehouse, the "sophisticated" cyber-attack was stopped "straight away" after it was discovered on Wednesday afternoon.
The affected division operates three websites: OneSTopPhoneShop.com, e2save.com and Mobiles.co.uk. It also provides services to iD Mobile, TalkTalk Mobile, Talk Mobile and some Carphone Warehouse customers.
Dixons Carphone, which owns Carphone Warehouse, has apologised for the attack. They say additional security measures have been brought in and the affected websites have been taken down.
Details likely to be sold on
Some customers have complained, saying they should have been made aware of the breach when it was first detected. However, Technology analyst Tom Cheesewright told the BBC that the company may have been trying to assess the level of damage before they made any announcements.
"I don't think we'll know until the information Commissioner's Office looks at this – whether they did the right thing, whether they were prudent in waiting a few days," he said.
He also said that any data stolen was likely to be sold on.
"There's a ready market in this sort of information. You might pay £5 to £10 for one set of credit card details, maybe twice that for a full identity," he explained.
He added that information may then be used to shop or take out loans. "It's a very good start for a full case of identity theft," he warned.
At 11:30 BST, share prices at Dixons Carphone were down 0.77 per cent to 452.50p.
GAIN Capital UK Limited (trading as “City Index”) is an execution-only service provider. This material, whether or not it states any opinions, is for general information purposes only and it does not take into account your personal circumstances or objectives. This material has been prepared using the thoughts and opinions of the author and these may change. However, City Index does not plan to provide further updates to any material once published and it is not under any obligation to keep this material up to date. This material is short term in nature and may only relate to facts and circumstances existing at a specific time or day. Nothing in this material is (or should be considered to be) financial, investment, legal, tax or other advice and no reliance should be placed on it.
No opinion given in this material constitutes a recommendation by City Index or the author that any particular investment, security, transaction or investment strategy is suitable for any specific person. The material has not been prepared in accordance with legal requirements designed to promote the independence of investment research. Although City Index is not specifically prevented from dealing before providing this material, City Index does not seek to take advantage of the material prior to its dissemination. This material is not intended for distribution to, or use by, any person in any country or jurisdiction where such distribution or use would be contrary to local law or regulation.