The European Commission said Wednesday it was fining seven companies 388 million euros (490 million dollars) for running a cartel in the market for bleaching chemicals.

The EU competitions regulator found that the companies had broken EU cartel rules in the 470-million-euro market for hydrogen peroxide and perborate between 1994 and 2000.

"Cartels are unacceptable corporate behaviour that deprive customers of the benefits of the single market," said Competition Commissioner Neelie Kroes.

"Directors and shareholders alike should ask why these practices were allowed to continue," she added.

The biggest individual fine went to Solvay of Belgium with 167 million euros, plus 26 million euros from a joint venture with Italian firm Edison that it has since bought out.

The company slammed its fine as excessive and vowed therefore lodge an appeal before an EU court.

Solvay was followed by Arkema of France with a fine of 79 million euros, Edison of Italy with 58 million euros, Kemira of Finland with 33 million euros, Akzo Nobel of the Netherlands and FMC Foret of the United States both with 25 million euros. Snia of Italy was fined one million euros.

German group Degussa escaped fines because it informed on the cartel, and French company Air Liquide was not fined because it left the market in 1998.

The EU competition watchdog said it had imposed tougher fines on Arkema, Edison and Solvay because they were repeat offenders.

The decision to crack down on the companies was based on evidence from a 1995 meeting where the rivals held talks about "a model for sharing out among producers," a commissiion statement said.

It pointed to further evidence from a 1997 meeting in a Brussels restaurant to coordinate price increases and a 1998 gathering where high-level company officials congratulated themselves on how well the arrangement was working.