The settlement follows from a 2010 internal investigation by RBS into its historical US dollar payment processes and controls, according to the BBC.

The violations took place between 2005-09, the US Treasury said.

In a statement, RBS said it “acknowledges and deeply regrets these failings”.

RBS found that bank procedures removed location information on payments made to US financial institutions from countries such as Iran and Cuba.

According to the New York Division of Financial Services, RBS employees in the UK “received written instructions containing a step-by-step guide on how to create and route US dollar payment messages involving sanctioned entities through the United States to avoid detection”.

In total, more than 3,500 transactions, totalling approximately $523m, were routed through New York banks in violation of US sanctions.