* Taxation of Dutch ports could breach EU competition rules
* France, Belgium warned over their tax treatment of ports
* EU executive could broaden investigation to other EU ports
By Julia Fioretti
BRUSSELS, July 9 The European Union's competition watchdog on Wednesday opened an investigation into tax exemptions granted to ports in the Netherlands and warned France and Belgium their taxation of ports may breach EU state aid rules.
The EU will look into whether corporate tax exemptions for some Dutch public companies - including the operator of Rotterdam port, Europe's biggest by annual cargo - breach the EU's rules against governments giving unfair advantages to some companies, thereby distorting competition.
"There should be a level playing field between ports in the EU," said Joaquin Almunia, the EU's antitrust commissioner.
"The Commission needs to verify that public companies, including port operators, in the Netherlands are not given more favourable tax treatment than their private competitors."
If the tax exemptions are found to in breach of EU state aid rules, Brussels can ask the Dutch government to change the way its ports are taxed.
The Commission warned France and Belgium it had concerns about the tax treatment of their ports and also requested further information from Germany on the same issue.
The investigation into the taxation of ports across the EU will continue, the watchdog said, in a sign other countries could also come into its firing line.
The Commission had already asked the Dutch government in May last year to abolish the corporate tax exemption for public companies, arguing it gave them an unfair advantage over their private counterparts.
While the Netherlands agreed to comply with the EU's request, it kept the exemption in place for five ports: Rotterdam, Amsterdam, Zeeland, Groningen and Moerdijk.
(Reporting by Julia Fioretti, editing by David Evans)