The European Commission has fined five city of London-based banks €1.07 billion after traders rigged the foreign exchange market between 2007 and 2013.

Four of the culprits – Barclays, RBS, Citigroup and JP Morgan – were fined €811 million in all.

Three banks known as the Essex Express cartel – Barclays and RBS, plus MUFG – were fined €258 million.

A sixth bank, UBS, was excused financial penalties for revealing the existence of the cartels.

Chatrooms

The traders used online chatrooms to plan their rigging strategy and knew each other personally.

EU Competition Commissioner Margrethe Vestager said the banks' behaviour "undermined the integrity of the sector at the expense of the European economy and consumers".

Lawyer Lambros Kilaniotis, a partner at City-based firm RPC, said the fine was "an open invitation for parties who may have been impacted by these cartels to sue these banks".

"If they haven't already, any party involved in forex trading, such as institutional investors, pension funds and large corporates, should now be reviewing what losses they have incurred," he added.