(Adds details from industry group)
By Bart H. Meijer
AMSTERDAM, July 12 (Reuters) - The Dutch competition watchdog said on Wednesday it was investigating a possible illegal, price-fixing cartel by fuel companies in ports in the Netherlands and Belgium.
The watchdog, known by its Dutch acronym ACM, said it had visited some of the dozens of companies active in fuel production, transportation, storage and trading in Rotterdam, Antwerp and Amsterdam after receiving information from the police.
The ACM, which did not name any of the companies, said in a statement it had asked anyone with relevant information to come forward.
The port of Rotterdam is Europe's largest bunkering port, as well as one of the top three bunkering ports worldwide.
Listed Dutch tank storage company Vopak is among the companies active in the sector, but said in an email it didn't expect to be impacted by the investigation, since it's not involved in "the pricing and trading of bunker fuels".
Industry group Nove, which represents independent fuel traders in Rotterdam and Amsterdam with a combined market share of 40 percent, said two of its members had been visited by the ACM and that other companies had received a questionnaire.
Nove, which also declined to name the companies involved, said it was surprised by the investigation. "Prices for maritime fuels in Rotterdam are amongst the lowest in the world and are very transparent", the organisation's head, Erik de Vries, said.
Fines for participants in a cartel can amount to 40 percent of a company's worldwide annual revenue, or to 900,000 euros for people in charge of the deals. Fines can be lowered for companies that admit wrongdoing, the ACM said.
The possible shipping fuel cartel is not the first on the radar of the ACM in the port of Rotterdam, Europe's largest.
In recent years, it opened inquiries into possible price-fixing schemes involving tugboat companies and a large container terminal. These investigations are still ongoing, a spokesman for the ACM said on Wednesday. (Reporting by Bart Meijer; Editing by Mark Potter and David Evans)