Barclays, Citigroup, J.P. Morgan, MUFG and Royal Bank of Scotland have been fined a total of 1.07 billion euros ($1.2 billion) by EU antitrust regulators for rigging the spot foreign exchange market for 11 currencies.

Swiss bank UBS was exempted from a 285 million euro fine since it alerted the existence of two cartels to the European Commission. The financial industry has been hit with billion euro fines worldwide in the last decade for rigging key benchmarks.

"Companies and people depend on banks to exchange money to carry out transactions in foreign countries. Foreign exchange spot trading activities are one of the largest markets in the world, worth billions of euros every day," EU Commissioner Margrethe Vestager said in a press release Thursday.

"Today we have fined Barclays, The Royal Bank of Scotland, Citigroup, J.P. Morgan and MUFG Bank and these cartel decisions send a clear message that the Commission will not tolerate collusive behavior in any sector of the financial markets. The behavior of these banks undermined the integrity of the sector at the expense of the European economy and consumers," Vestager added.

The EU investigation that has been ongoing for the past six years revealed that some individual traders from various banks in charge of forex trading — a form of trading executed on an intra-day basis — exchanged sensitive information and trading plans through various online professional chat rooms.

"The information exchanges.....enabled them to make informed market decisions on whether to sell or buy the currencies they had in their portfolios and when," the Commission said in its report.

It further stated that most of the traders knew each other on personal basis and logged into multilateral chatrooms on Bloomberg terminals for the whole day, engaging in extensive conversations about a variety of subject, including updates on their trading activities.

Barclays declined to comment when contacted by CNBC. Meanwhile, a spokesperson from RBS told CNBC the bank is happy to reach a settlement with the regulators.

"Today's fine is a further reminder of how badly the bank lost its way in the past and we absolutely condemn the behaviour of those responsible. This kind of behaviour has no place at the bank we are today; our culture and controls have changed fundamentally during the past ten years," the spokesperson said.

A similar case with the U.S. regulators is ongoing where Barclays, BNP Paribas, Citigroup, J.P. Morgan, Royal Bank of Scotland and UBS have entered related guilty pleas, and been collectively fined more than $2.8 billion.

U.S. regulators said the foreign exchange rate rigging was allegedly done through chat rooms with such names as "The Cartel," "The Mafia" and "The Bandits' Club," through tactics with such names as "front running," "banging the close," "painting the screen" and "taking out the filth."

Shares of Barclays and RBS were trading lower, but UBS edged a bit higher on the news. Meanwhile, J.P. Morgan and Citigroup shares were down slightly in pre-market trading.

—Reuters contributed to this report