The European Commission on Wednesday fined 11 producers of high-voltage power cables a total of 300 million euros for operating a cartel that secretly shared out the global market.
"These companies knew very well that what they were doing was illegal. This is why they acted cautiously and with great secrecy," said EU Competition Commissioner Joaquin Almunia said.
The EU said six European, three Japanese and two Korean firms -- that all make up the world's biggest high voltage cable producers -- of sharing markets and allocating customers between themselves.
The companies involved in the scheme were Japanese companies VISCAS and JPS, Nexans of France and Italian company Prysmian, which was previously owned by investment bank Goldman Sachs.
Swiss company ABB received full immunity, having been the first company to reveal the existence of the cartel.
The investigation began with surprise raids on the companies in January 2009 and revealed that the producers had entered into agreements from 1999 that guaranteed home markets.
"Whenever Japanese and Korean companies received requests from European customers, they would notify their European counterparts and decline the bid," the commission said in a statement.
According to the EU, the firms met regularly in hotels across Europe and south-east Asia and agreed price levels to ensure that the allocated company would bid the lowest price and the others offer a bid that was unattractive to the customer.
The equipment involved in the case are cables used to connect generation capacity, such as wind farms, to an electricity grid or to connect national grids between different countries.