The Dutch leader told reporters "the problem is not only France and the Netherlands," referring to the two nations voting "no" to the constitution in referendums last year.

"If you had referendums in Poland, the UK or Denmark, I'm not sure what would happen," he said, referring to votes which were initially planned but called off after the French and Dutch referendums.

The remarks were aimed at critics who hold France and the Netherlands responsible for holding up further ratification of the EU charter, which has so far been ratified by 13 member states.

Dutch foreign minister Bernard Bot earlier this month declared the constitution "dead," a remark which Mr Balkenende declined to repeat, but backed up by saying it is "unrealistic that the constitution will be put to voters a second time."

Mr Bot's remark drew strong criticism particularly from the European Parliament, with Hans-Gert Pottering, the leader of the centre-right EPP faction, saying "I have no understanding at all for such statements. It should be his responsibility to propose ways how the constitution can be transposed into legal and political reality."

But The Hague has so far refused to take any political initiative, or even to provide a political assessment of what it thinks the deeper causes of the Dutch "no" are.

"It is too early to make statements," Mr Balkenende said, adding he wants to await results of ongoing government research into Dutch people's attitude to Europe, expected for the end of April.

French tenacity

The Dutch hesitation contrasts sharply with the more pro-active stance of the French, who have drawn clearer analysis and policy responses from their "non."

Dominique de Villepin, France's prime minister, indicated in a speech in Salzburg "The French people did not say no to Europe. They expressed fears and anxiety but also aspirations."

His comments indicate that Paris believes its citizens are particularly uneasy over EU enlargement, but want Europe to better protect them at the same time, creating the need for deeper integration.

Referring to the bloc's previous expansion to ten new states in 2004, he stated "enlargement was not sufficiently prepared on the economic front," adding "we went ahead without deepening."

On the ongoing EU accession talks with Turkey, he stated "the outcome of the process will remain open, and the last word will be with the French people," referring to Paris' pledge to hold a referendum on Turkish membership.

While the French government is keen to show its citizens it has taken enlargement fatigue seriously, it is at the same time taking initiatives to "deepen" integration in individual policy areas.

Mr de Villepin singled out tax harmonisation, a common EU border police and an EU energy policy as examples of fresh European projects he has in mind.

He also proposed a UNESCO-style "European heritage" trademark for European monuments.

French president Jacques Chirac earlier this month said he wishes to see closer co-operation in "internal security and justice, external action and better involvement of national parliaments in the European decision-making process."