The council's opinion is likely to be followed by the Dutch cabinet, which is expected to discuss the issue in a meeting on Friday (14 September).

The Council of State's advice is however not binding for the Dutch parliament, which could still decide to hold an own-initiative poll.

It was the Dutch parliament which - against the wishes of prime minister Balkenende - organised the 2005 referendum on the EU constitutional treaty, which ended in a resounding "no" vote.

In the parliament's lower house, there could be a majority for a second treaty referendum, with prominent members of the country's second largest political faction, the Labour party, recently coming out in favour of the idea.

But a referendum bill could eventually be blocked in the senate, which is more conservative in its composition. Christian Democrat and Liberal senators are seen to be against having a referendum.

The issue is meanwhile set to cause tension in the Netherland's centrist coalition government, which includes prime minister Jan Peter Balkenende's Christian Democrats – who oppose a new EU referendum – and Labour, which is under increasing pressure to support a treaty poll.

This week's Council of State opinion can be seen as a boost to Mr Balkenende, who has been involved in some clever political manoeuvring to avoid a second EU referendum.

The 2005 EU constitution referendum came after the Council stated that the document was "to a certain extent" comparable to a change in the Dutch national constitution.

Consequently, in the re-negotiations on the failed EU constitution, Mr Balkenende pressed for the new treaty to be stripped of quasi-constitutional elements, such as the name "constitution" and references to the EU flag and anthem.

Czechs question ratification tempo

Meanwhile, the Czech government has questioned the EU's target date for the ratification of the new treaty - set for 2009, ahead of the European Parliament elections due in June.

"We do not want to improvise during our presidency," said Alexander Vondra, the Czech secretary for EU affairs, referring to the country's six-month term at the EU's helm in the first half of 2009, the CTK agency reported.

Mr Vondra suggested that putting the treaty in force within a 12-month period - rather than within the 18-24 months that is normally the case - would be a "record tempo" and hard to achieve.

The current Portuguese EU presidency is hoping to have the document wrapped up by this December so ratification can start quickly next year.

Prague had expressed concerns about the ambitious timetable before, but other EU member states argue the new institutional rules should be introduced just ahead of the EU assembly's 2009 elections.