Exit polls released after the polls closed on Thursday suggested that the Party for Freedom, whose leader Geert Wilders ran on an anti-Islam ticket, will claim four of the country’s 25 seats in Brussels.

Prime Minister Jan Peter Balkenende's Christian Democrat party looked set to retain five of their current seven seats but Labour, one of the three parties who make up the ruling coalition government, lost four of its seven seats.

The left-wing party D66 picked up two new seats and will now have three MEPs.

The European Commission, however, is to ask the Dutch government to explain why the results were released early.

Only the Netherlands and the United Kingdom voted early and results were not due to be released until the ballot boxes had closed in the other 25 EU nations on Sunday.

"We are going to ask for clarification from the Netherlands," said Amadeu Altafaj Tardio, a senior spokesman for the European Union's executive arm.

"We want to know who published what information, at what moment, and to whom. We will give the interested party a chance to explain itself before we make a decision on any action."

"We are going to verify if there's been a violation of EU rules. Then we'll see what we'll do," he said.

The Netherlands will face a fine if found to be in breach of the bloc’s rules.