Third teen arrested over cyber attack on UK's TalkTalk

British police said Tuesday they had arrested a third teenager in connection with a cyber attack on Internet and telephone provider TalkTalk that put millions of customers' data at risk.

The 16-year-old boy was arrested in the east England city of Norwich on Tuesday evening and taken to a police station while the property was searched, according to a statement from the Metropolitan Police.

It comes after the arrests last week of a 16-year-old boy from west London, a 15-year-old boy in Northern Ireland, and a 20-year-old man in Staffordshire in central England. All three have since been released on bail.

The personal data of some four million customers of TalkTalk are feared to have been breached in the hack, which was the third cyber attack on the firm in eight months in which customers' data was stolen.

TalkTalk has said that it is not sure how many customers were affected but that data including names, bank details and addresses could be at risk.

The company has said that not all information on customers was encrypted, and described the attack as "significant and sustained".

Police are working together with serious organised crime body the National Crime Agency and cyber crime detectives on the case.

Investigators are examining a ransom demand sent to TalkTalk and purporting to be from the hacker, though the company is not sure if the demand was genuine.