Barclays and RBS are among five banks fined over €1bn by the European Commission after traders colluded to rig the foreign exchange market.

Total fines of €1.07bn (£935m) have been imposed by the European Commission against, Barclays, RBS, Citigroup, JP Morgan and MUFG.

A sixth bank, UBS, avoided fines as it provided evidence of the trading cartel’s activities.

The European Commission started investigating suspicious foreign exchange trading activity in September 2013.

They discovered some foreign exchange traders using online chatrooms to exchange future trading plans and coordinate strategies.

The Commission said the conversations “enabled them to make informed market decisions on whether to sell or buy the currencies they had in their portfolios and when”.

Traders were found to have exchanged customer information, details of orders, prices applied to each transaction, current trading status at each bank and future trading plans.

Competition Commissioner Margrethe Vestager said the banks’ conduct “undermined the integrity of the sector at the expense of the European economy and consumers”.

These fines follow similar penalties issued by UK, US and Swiss regulators in 2014 for manipulating foreign exchange markets.