Major banks which took part in a foreign exchange spot-trading cartel using a chat room called 'Essex Express 'n the Jimmy' have been handed a £930 million fine.

The chat was so called because all the traders involved, except for one, lived in Essex and regularly met up on the train to and from London.

Barclays and Royal Bank of Scotland (RBS) are among the five banks fined.

Citigroup, JP Morgan and MUFG were also fined by the EU antitrust group in two settlements, as announced by the European Commission.

Barclays, RBS, JPMorgan and Citigroup were hit with a combined fine of £708.6 million in the first settlement.

The second settlement saw a £225.1 million fine slapped on Barclays, RBS and MUFG Bank (formerly Bank of

Tokyo-Mitsubishi).

The commission said the banks colluded on trading strategies to rig the spot foreign exchange market for 11 currencies.

Swiss bank UBS was involved but not fined after it alerted the EC about the two cartels.

The investigation revealed that some individual traders in charge of foreign exchange spot trading for currencies on behalf of their associated banks exchanged sensitive information and trading plans.

The first infringement ran from December 2007 to January 2013, while the second ran from December 2009 to July 2012, the commission said.

Commissioner Margrethe Vestager said: "Companies and people depend on banks to exchange money to carry out transactions in foreign countries.

"Today we have fined Barclays, the Royal Bank of Scotland, Citigroup, JPMorgan and MUFG Bank and these cartel decisions send a clear message that the commission will not tolerate collusive behaviour in any sector of the financial markets.

"The behaviour of these banks undermined the integrity of the sector at the expense of the European economy and consumers."