BRUSSELS: The European Commission fined Germany's EON and GDF Suez of France on Wednesday a total of over a billion euros for agreeing to stay out of each other's markets in breach of EU rules, a statement said.

In the first ever anti-trust fines imposed in the energy sector, the commission fined EON and GDF Suez 553 million euros (769 million dollars) each -- the second-biggest financial sanction Brussels has imposed in a cartel case.

The EU's top competition regulator said the two had "agreed in 1975, when they decided to jointly build the MEGAL pipeline across Germany to import Russian gas into Germany and France, not to sell gas transported over this pipeline in each other's home markets."

It said: "They maintained the market-sharing agreement after European gas markets were liberalised, and only abandoned it definitely in 2005."

Commission investigators raided the premises of the two companies in 2006, and the EU watchdog launched an anti-trust inquiry in July 2007.

Brussels said that the market-sharing agreement had helped both hold strong positions in the French and German gas markets as they were being liberalised and so deprived consumers of price competition and choice of supplier.

"This agreement deprived customers of more price competition and more choice of supplier in two of the largest gas markets in the EU," said EU Competition Commissioner Neelie Kroes.

"Market sharing is one of the worst types of antitrust infringement," she said in the statement. "The commission has no alternative but to impose high fines."