NatWest has been fined over £264m after the bank became the first lender to plead guilty to criminal charges for violating anti-money laundering (AML) laws in connection with a gold dealership.

The bank pleaded guilty in October to failing to prevent alleged money laundering of almost £400m by a single customer, and this should act as a warning to all businesses, including estate agents, that they must adhere to the requirements of AML legislation.

NatWest previously said that it regrets failing to “adequately monitor and therefore prevent money laundering by one of our customers between 2012 and 2016”.

The case was brought by the Financial Conduct Authority (FCA) which alleged the bank failed to monitor suspect activity by a client that deposited about £365m in its accounts over five years, of which £264m was in cash.

The criminal action, first announced by the FCA in March, was the first against a bank under a 2007 money laundering law.

At Southwark crown court on Monday, Mrs Justice Cockerill fined the bank £264,772,620, ordered it to pay £4,297,466 in costs and made a £460,047 confiscation order.

“Although in no way complicit in the money laundering which took place,” the judge said. “Without the bank’s failings the money could not have been laundered.”

NatWest CEO Alison Rose said in a statement: “NatWest takes its responsibility to prevent and detect financial crime extremely seriously. We deeply regret that we failed to adequately monitor one of our customers between 2012 and 2016 for the purpose of preventing money laundering.

“While today’s hearing brings an end to this case, we will continue to invest significant resources in the ongoing fight against financial crime.”