HSBC has confirmed it is to pay US authorities $1.9bn (£1.2bn) in a settlement over money laundering, the largest paid in such a case.

A US Senate investigation said the UK-based bank had been a conduit for "drug kingpins and rogue nations". Money laundering is the process of disguising the proceeds of crime so that the money cannot be linked to the wrongdoing. HSBC admitted having poor money laundering controls and apologised.

"We accept responsibility for our past mistakes," said HSBC group chief executive Stuart Gulliver in a statement. "We have said we are profoundly sorry for them, and we do so again." The bank said it had spent $290m on improving its systems to prevent money laundering and clawed back some bonuses paid to senior executives in the past.

It also said it expected to reach an agreement with the UK's Financial Services Authority shortly. Last month it announced it had set aside $1.5bn to cover the costs of any settlement or fines.

The news followed the announcement of a similar but much smaller settlement with UK-based Standard Chartered bank, which will pay $300m in fines for violating US sanctions.