The Metropolitan Police has opened a criminal investigation after internet provider TalkTalk sustained a “significant and sustained cyber attack”, which has led to fears that customers’ details might have been hacked.
It sent shares in the telecoms firm sliding more than 11 per cent in Friday morning trading.
The issue first appeared at 3pm on Wednesday. However, according to outage website Down Detector, customers were still experiencing service problems on Thursday.
Initially, Talk Talk, which has four million customers in the UK, said: "We have taken down talktalk.co.uk temporarily, and normal service will be resumed as soon as possible. Our taking down of the website is not related to a broadband outage."
However, following reports of the Met investigation, the internet provider said in a statement: "Today [Thursday 22 October], a criminal investigation was launched by the Metropolitan Police Cyber Crime Unit following a significant and sustained cyberattack on our website yesterday.
"That investigation is ongoing, but unfortunately there is a chance that some of the following data has been compromised: names, addresses, date of birth, phone numbers, email addresses, TalkTalk account information, credit card details and/or bank details. We are continuing to work with leading cyber crime specialists and the Metropolitan Police to establish exactly what happened and the extent of any information accessed."
TalkTalk boss Dido Harding said: “TalkTalk constantly updates its systems to make sure they are as secure as possible against the rapidly evolving threat of cyber crime, impacting an increasing number of individuals and organisations.
"We take any threat to the security of our customers’ data extremely seriously and we are taking all the necessary steps to understand what has happened here. As a precaution, we are contacting all our customers straight away with information, support and advice around yesterday’s attack."