A 16-year-old boy from London has been arrested in connection with the investigation into alleged data theft from TalkTalk.
Police confirmed officers carried out a search at a residential property in Liverpool in connection with the cyber attack.
It comes after a boy of 15 was held in Northern Ireland on suspicion of offences under the Computer Misuse Act over the same data breach.
The telecommunications company shut down its site following what it described as a "significant and sustained" attack in which customer details may have been stolen.
On 23 October it said it may have been the target of a ransom demand by the hackers.
The company's four