TalkTalk should have notified the personal data watchdog sooner about the cyber attack on its systems, Information Commissioner Christopher Graham said.

The Information Commissioner's Office (ICO) was informed about the data breach at 4.30pm on Thursday, but the attack began on Wednesday.

Mr Graham said the delay was one of the issues the ICO would examine in its investigation into the "very serious data breach".

But he told BBC Radio 4's World At One: "I wish we had heard a little bit earlier and we could have been more 'out there' giving advice to consumers about what they need to protect their personal information."

The ICO is already investigating TalkTalk over two previous data breaches, Mr Graham said.

"The job of the Metropolitan Police in this case is to investigate the theft, the job of the Information Commissioner's Office is to investigate why the thieves were able to get away with it," he said.

TalkTalk has been unable to say whether customers' personal data was encrypted and Mr Graham indicated that if the information was not secure it could lead to a bigger penalty from the watchdog.

Mr Graham said: "There isn't an off-the-peg solution that renders everything secure and in some cases encrypting everything would probably be excessive.

"But the big civil monetary penalty we imposed on the Sony Corporation for the PlayStation incident was involving the lack of encryption of customer data and that cost them £200,000.

"People have got to take this seriously."

He said the incentive for a firm to act was the potential damage to its reputation rather than simply the prospect of a fine.

"The incentive is the blow to the reputation. We have already seen the TalkTalk share price falling today, even before we have conducted our investigation.

"We are increasingly operating in a digital economy and the terms on which all these companies get our business is by showing that they can look after it. If they let us down then we can shop elsewhere."