Mr Lund's crusade against the European Union Constitution started already on Tuesday, 12 August, when parts of an article, to be published on the European Parliament website, were leaked to Politiken.

"We are 5 per cent from a real European federal state and claims about the independence of countries will have a more and more hollow ring", Mr Lund wrote in the article.

"I am not sure the citizens are in any way aware of what is going on. All the changes are duly labelled in calming phrases", Mr Lund wrote.

Torben Lund is not known to be eurocritical and his article has caused some raised eyebrows. He now faces a tough battle within his party for going against the party line and not backing the Constitution.

The row over the EU Constitution has come at a very bad moment for the Social Democrats. Later this week negotiations are to begin with the liberal-led government on positions in the upcoming Intergovernmental Conference which will finalise the draft constitution. The IGC, which brings together high-level government representatives, will start in October.

The Danish Prime Minister, Anders Fogh Rasmussen, last week promised that the Danes will decide on the Constitution in a referendum next year.

Torben Lund is a former Danish minister and has been the leader of the Danish Social Democrat's in the European Parliament since 1999.

He is also the treasurer of the Social Democrat PES-group in the European Parliament.