A 17-year-old boy has been arrested in connection with the cyber security incident affecting Transport for London (TfL), the National Crime Agency (NCA) said.

On Thursday TfL said that some customers’ sort codes and bank account details could have been accessed by hackers during an “ongoing cyber security incident”.

The NCA said the teenager was arrested in Walsall on 5 September.

The transport operator first reported a cyber attack on 2 September.

The NCA said the teenager was arrested on suspicion of Computer Misuse Act offences.

He was questioned by NCA officers and has since been bailed.

The NCA said it was working with TfL and the National Cyber Security Centre to minimise the risks to customers.

Paul Foster, head of the NCA’s National Cyber Crime Unit, said: “Attacks on public infrastructure such as this can be hugely disruptive and lead to severe consequences for local communities and national systems.”

TfL’s chief technology officer Shashi Verma said on Thursday that a “limited number of customers” may have had bank account numbers and sort codes accessed.

He said those impacted would be contacted directly.

Mr Verma said an investigation into the cyber attack was taking place alongside the National Crime Agency and the National Cyber Security Centre.

“Although there has been very little impact on our customers so far, the situation continues to evolve and our investigations have identified that certain customer data has been accessed,” he said.

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