UK police have arrested a 15-year-old boy in Northern Ireland in connection with the cyber attack on TalkTalk.
The boy was taken into custody at a County Antrim police station where he will be questioned in relation to the cyber attack.
The investigation involved the Police Service of Northern Ireland (PSNI), and detectives from the Metropolitan Police Cyber Crime Unit (MPCCU).
A statement from TalkTalk said: "We know this has been a worrying time for customers and we are grateful for the swift response and hard work of the police. We will continue to assist in the ongoing investigation."
The breach has potentially resulted in the theft of personal data, including bank and credit card details, from 4 million customers. The company said bank account numbers and sort codes may have been accessed by the hackers.
TalkTalk has partnered with one of the three main credit agencies, Noddle, to provide its customers with 12 months’ free credit monitoring.