THE taxpayer-owned Royal Bank of Scotland has been fined a further £430 million ($669 million) by the US federal reserve – on top of a £339 million penalty last November – after agreeing to plead guilty to criminal charges including manipulating the foreign exchange market.

RBS chairman Philip Hampton said three people had already been sacked and two suspended over the charges.

“We strongly condemn the actions of those responsible and regret the control failings that allowed such misconduct to take place,” he said.

“This episode has exposed serious shortcomings at both individual and collective levels from which we continue to learn. As part of this effort, we are committed to implementing further improvements to systems and controls.

“We are continuing thorough investigations into the conduct of employees in this part of the business. As a result, we have dismissed three people and suspended two more pending further investigation.

“This work is on-going and will take into account the findings contained in these settlements.”

Chief executive Ross McEwan added that the “serious misconduct” at the heart of yesterday’s announcements had “no place in the bank that I am building”.

“Pleading guilty for such wrongdoing is another stark reminder of how badly this bank lost its way and how important it is for us to regain trust,” said McEwan.

“To regain that trust we are putting the interests of our customers at the heart of this business and its culture. It has taken far longer than anyone hoped to root out all the past conduct problems and practices and as a result we still have significant challenges on the horizon.

“We are determined to learn the lessons from our past mistakes and to hold those responsible fully to account for their actions.” RBS was one of five banks to be hit with fines in a raft of new settlements over their involvement in the rigging of global currency markets in the latest scandal to hit the industry.

Barclays agreed a £1.53 billion fine, including a record £284.4 million to the UK’s Financial Conduct Authority (FCA). US banks JP Morgan Chase & Co and Citigroup, along with Swiss bank UBS were fined a total of £3.7 billion for their role in the scandal.

The FCA imposed its highest ever penalty against Barclays for failing to control business practices in its foreign exchange business in London. Its settlement was greater than the other banks as it held off from agreeing fines in the previous round in November.

Georgina Philippou, the FCA’s acting director of enforcement and market oversight, said: “This is another example of a firm allowing unacceptable practices to flourish.

“Instead of addressing the obvious risks associated with its business, Barclays allowed a culture to develop which put the firm’s interests ahead of those of its clients and which undermined the reputation and integrity of the UK financial system.”

The FCA said its fine would have been 20 per cent higher – at £335.5 million – had Barclays not settled when it did.

Four of the banks involved in the US and UK settlements – RBS Group, Barclays JP Morgan and Citigroup will plead guilty to conspiring to manipulate the price of US dollars and euros.

A Treasury spokesman said: “The Government created the tough new Financial Conduct Authority and gave it strong powers to take action wherever its rules are breached. The action taken on foreign exchange failings today, and in November last year, shows that the new, tougher regulatory system is working.”

The FCA said traders colluded with each other through chat rooms to rig rates, using names such as “the three musketeers”.

US regulators said Barclays had sacked four employees – three in London and one in New York – this month and urged the bank to fire four more who are currently based in New York.

Antony Jenkins, Barclays chief executive, apologised for the bank’s role in the scandal.

He said: “The misconduct at the core of these investigations is wholly incompatible with Barclays’ purpose and values and we deeply regret that it occurred.

“I share the frustration of shareholders and colleagues that some individuals have once more brought our company and industry into disrepute.”

The forex market is one of the largest markets in the world with a daily turnover of more than £3 trillion, 40 per cent of which takes place in London.