By Chris Morris BBC Europe correspondent

Four European Union countries who opposed the war in Iraq have announced plans for enhanced defence co-operation, including joint military planning and a multinational headquarters.

The leaders of France, Germany, Belgium and Luxembourg, who met in Brussels today, said all other EU countries were welcome to join them, and they had no intention of setting up an alternative to Nato.

"Our countries see their commitments in the European Union and in Nato as complementary commitments," said the French President, Jacques Chirac.

A force without the UK lacks credibility, say analysts

"In building a stronger Europe we obviously contribute to a stronger Atlantic alliance."

Despite scepticism from Britain and other EU member states which supported the war in Iraq, the participants in the mini-summit have promised to create a joint military planning system by next year, and a multinational headquarters for European military operations where Nato is not involved.

They also intend to set up their own rapid reaction force.

They want a pioneer group of EU countries to launch what they call a European Security and Defence Union, as part of any future EU constitution. All other member states would be encouraged to join.

In Nato, we do not have too much America, we have too little Europe and that is what we want to change with the proposals we have made German Chancellor Gerhard Schroeder

In other words, Europe's anti-war coalition has put down its marker for the future.

It wants the EU to have a stronger and more effective defence capability. And the four countries which gathered in Brussels are prepared to go it alone to begin with, if they have to.

They insist that their initiative is not anti-American or anti-Nato.

"In Nato, we do not have too much America, we have too little Europe", said the German Chancellor Gerhard Schroeder, "and that is what we want to change with the proposals we have made."

Sceptical nations

But other European countries, like the UK, Italy and the Netherlands, who weren't invited to this meeting, are sceptical.

The fear is that an initiative like this will set up a two or even a three speed Europe, with different groups of countries at different stages of development � possibly a recipe for chaos. But the Belgian Prime Minister Guy Verhofstadt, who hosted this summit argued that the EU has to start somewhere.

If it had waited for Britain to join the euro, he pointed out, then the single currency would not yet have been launched.

Some of the things which have been proposed in this new defence initiative are not too controversial � they have already been raised by delegates to the Convention on the Future of Europe.

Credibility

Proposals such as joint military training schemes, a disaster response unit, and a European armaments agency, will meet with little opposition.

But the idea of joint planning and a joint headquarters will ring a few alarm bells.

Britain and its allies have said they will do nothing to undermine Nato, and they do worry about deliberate duplication of effort.

And that poses a big challenge to the four countries who came to Brussels. They know that in the long term a European defence scheme which excludes Britain, the EU's strongest military power, would have precious little credibility.