German Chancellor Gerhard Schroeder said on Wednesday the ratification process of the EU constitution must continue after Dutch voters followed their French counterparts in rejecting the treaty.

Schroeder said he "respected but greatly regretted the decision of voters in the Dutch referendum", but strongly defended a treaty that Germany has already ratified.

"I am convinced that we need the constitution if we want a democratic, social-minded and strong Europe," he said.

"The ratification process must continue. Firstly out of respect for the nine countries which have already ratified it, and secondly because of the member states who still have to undergo the ratification.

"Every member state has the right, and a duty, to go through its own vote."

Germany, which like the Netherlands was a founding member of the European Union, last week completed the ratification of the constitution through its two houses of parliament but it was not put to a referendum.

Exit polls showed a resounding 62.6 percent of Dutch voters rejected the treaty on Wednesday.

Foreign Minister Joschka Fischer said the outcome was "regrettable and leaves Europe with a big challenge".

"It is not the end of the process of ratification and certainly not the end of European integration," he added.

Fischer said it must not be forgotten that German politicians had overwhelmingly approved the constitution "and Spain voted strongly in favour of the treaty with a large majority".

Therefore, "the causes and the consequences of the negative votes in France and the Netherlands must be carefully analysed", Fischer said.

A German conservative member of the European Parliament who helped to draw up the constitution said the "no" vote in the Netherlands could not be blamed solely on the result in France.

"The Dutch 'no' was encouraged by and took strength from the 'no' in France, Peter Altmaier, of the Christian Democratic Union (CDU), said.

"But the situation has been touch and go in the Netherlands for a long time.

"There is a crisis in the political system there, with the appearance of populist lists such as Pim Fortuyn's, as well as an economic and social crisis and a debate on the integration of immigrants."

Altmaier, the CDU's expert on the European Union, agreed with Schroeder, a Social Democrat, that despite the setbacks the process of ratifying the treaty must go on.

"As far as Europe is concerned, the situation is more complicated but the ratification process must continue so that every country in the EU has a chance to vote.

"Polls in Denmark and Poland are favourable to a 'yes' vote."

France rejected the constitution in a referendum on Sunday, prompting a change of prime minister and a cabinet shake-up.

The constitution is designed to provide a framework for an enlarged, 25-member European Union