Criminals could have stolen the bank and credit card details of more than four million people after a "significant and sustained" cyber attack on TalkTalk.

Police are now investigating after the broadband and phone provider reported it had been hacked on Wednesday.
The Metropolitan Police's Cyber Crime Unit is now investigating.
TalkTalk said it was now contacting customers to inform them they may be at risk.

The company also said the hackers may have accessed dates of birth, telephone numbers, names and addresses of its clients.

In a statement on its website, the company's managing director Tristia Harrison said: "We are very sorry to tell you that on Thursday 22nd October a criminal investigation was launched by the Metropolitan Police Cyber Crime Unit following a significant and sustained cyberattack on our website on Wednesday 21st October.

"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.

We would like to reassure you that we take any threat to the security of our customers’ data very seriously.

"Unfortunately cyber criminals are becoming increasingly sophisticated and attacks against companies which do business online are becoming more frequent."

The company said the website had now been made secure and it had contacted all the major banks which would be monitoring accounts for suspicious activity.