HSBC is investigating allegations that criminals used offshore accounts at its Jersey business for money laundering and tax evasion, the BBC reports.
The bank confirmed it is looking into the claims, which were revealed by the Daily Telegraph.
The Telegraph said tax authorities had were in possession of details of every British client of HSBC in Jersey - about 4,000 people are affected - after a whistleblower "secretly provided a detailed list of names, addresses and account balances earlier this week".
HSBC said it was investigating an alleged loss of certain client data in Jersey "as a matter of urgency", the BBC reports. It also said it had not been contacted by HRMC.
"Clamping down on those who try to cheat the system through evading taxes and over-claiming benefits is a top priority for us, and we value the information we receive from the public and business community," the bank told BBC news.
In a statement, HMRC said: "We can confirm we have received the data and we are studying it. We receive information from a very wide range of sources which we use to ensure the tax rules are being respected."
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