Dozens of traders face prosecution after five banks were fined £2.6billion yesterday for fixing currency markets.

Damning transcripts of City workers bragging about making ‘free money’ and laughing at ‘numpties’ not in on their scam were published by regulators.

Calling themselves ‘players’, ‘musketeers’ or members of the ‘A-Team’, the traders congratulate each other on ‘killing it’ with rigged deals.

Incredibly, their corrupt activities continued for more than a year after the authorities started dishing out an earlier £4billion in fines for the fixing of Libor interest rates.

Punishment: Five of the world's biggest banks, including HSBC, have been fined a total of £2bn for colluding to make money from the foreign exchange market

Shameful: New evidence published by the FCA today reveals the bragging messages sent by bankers online as they rigged deals

The illicit dealing was going on even as the big banks told MPs they had got to grips with past misconduct. Furious politicians insisted the culprits should be jailed.

‘They are lying to make money – it’s fraud and someone should go to jail,’ said LibDem MP John Hemming.

Andrea Leadsom, a Tory Treasury minister, said: ‘This is absolutely disgusting, I don’t know if corruption is a strong enough word for it.

‘Every taxpayer will be horrified to see that throughout the period of the financial crisis where they were bailing out the financial system, there was a group of foreign exchange traders and other traders who decided they would rig the system to suit their bonuses.’

Louise Cooper, a leading City commentator, said the traders sounded like ‘sniggering school boys’ and ‘kids let loose in a terribly expensive sweetie shop’.

Ross McEwan – chief executive of RBS, one of the banks implicated in the currency scam – said: ‘We had people working at this bank who did not know the difference between right and wrong, or worse, didn’t care about the distinction.’

The state-backed bank is investigating more than 50 current and past traders as well as dozens of supervisors and senior managers.

RBS was hit with £400million in fines and HSBC received a £390million penalty.

Fines for US giants JPMorgan and Citigroup, and Swiss bank UBS, took the bill to £2.1billion.

UK and US regulators are also investigating Barclays, which has refused to accept the terms of settlement.

Shocking: One conversation between traders led to a deal that made giant UBS $513,000 and one trader joked about how a colleague bragged about his bonuses

Martin Wheatley, who heads the Financial Conduct Authority, said traders had tried to game the £3trillion-a-day foreign exchange market.

‘Today’s record fines mark the gravity of the failings we found and firms need to take responsibility for putting it right,’ he added.

‘They must make sure their traders do not game the system to boost profits or leave the ethics of their conduct to compliance to worry about.’

FCA chief executive Martin Wheatley

The FCA said it could not say how many individuals were involved in the scam which lasted from January 2008 to October 2013.

But it is widely expected to be more extensive than the Libor interest rate scandal, for which a string of banks including Barclays started to be fined in June 2012.

In the latest scandal, RBS failed to act despite receiving complaints from clients about foreign exchange trading as far back as 2010.

A year later a dealer at the bank questioned the sharing of confidential client information at the bank. More than 30 staff at banks across the world have been suspended.

George Osborne said the Government would offer its full support to a Serious Fraud Office investigation, which was launched in July but is now expected to be escalated.

Pledging that the money raised from the fines would be used for the ‘wider good’, the Chancellor said: ‘We are absolutely determined to clean up corruption in the City by the few so that financial markets work for everyone and we have a banking system that works for everybody.’

The FCA began its probe a year ago after whistleblowers compared the foreign exchange market to the ‘Wild West’ and described how traders were taking advantage of the lack of rules and regulations.

Stevie Loughrey, of the law firm Carter-Ruck, said the FCA’s remediation efforts ‘will not comfort bank customers with significant losses’.

UBS, Citibank, HSBC, RBS and JP Morgan were fined £2billion and Barclays will also be fined at a later date