Santander UK, the British arm of the Spanish banking company Santander, has been fined by the Financial Conduct Authority (FCA), after the regulator found business banking customers were affected by failures in anti-money laundering measures.
The FCA said the bank "failed to properly oversee and manage" these systems, which led to the oversight of more than 560,000 business customers being affected.
The bank has been fined £107.8 million ($132 million) for what the FCA called "serious and persistent gaps" in its anti-money laundering controls.
The measures Santander had in place that verify the information provided by customers about the business they were doing was ineffective, the FCA said.
The systems failures led to more than £298 million passing through the bank before it closed accounts.
"Santander's poor management of their anti-money laundering systems and their inadequate attempts to address the problems created a prolonged and severe risk of money laundering and financial crime," said Mark Steward, executive director of enforcement and market oversight at the FCA.
"As part of our commitment to prevent and reduce financial crime, we continue to take action against firms which fail to operate proper anti-money laundering controls," he added.
Santander UK chief executive Mike Regnier said: "We are very sorry for the historical anti-money laundering (AML) related controls issues in our business banking division between 2012 and 2017 highlighted in the FCA's findings.
"While we took action to address our AML issues once they were identified, we accept that our AML framework at the time should have been stronger," he added.