Five of the biggest EU countries have tasked foreign relations chief Catherine Ashton with making plans for an EU military command centre despite British objections.

Foreign ministers from the group - France, Germany, Italy, Poland and Spain - in a letter dated 2 September and seen by EUobserver urged Ashton to: "Examine all institutional and legal options available to member states, inlcuding permanent structred co-operation, to develop critical CSDP [Common Security and Defence Policy] capabilities, notably a permanent planning and conduct capability."

They added: "We would appreciate if you present conclusions of the work ... in early autumn with a view to achieving tangible results by the end of the year."

Permanent structred co-operation is an EU treaty option that allows nine or more member states to press ahead on an EU project without the others.

It was first used earlier this year on EU divorce and patent laws.

Setting up a non-EU-27 command hub for EU military missions would be a major step toward what EU jargon calls a "multi-speed Europe". But plans afoot to create joint economic governance among the 17 euro-using countries are likely to put even the military project into the shade.

The letter justified the plan by reference to the Arab Spring and the economic crisis.

"Instability and the proliferation of crises on the one side, and scarcity of resources on the other side, have significantly raised expectations as to the effectiveness and credibility of EU actions," it said. The ministers added that EU talks in July "proved there is a strong political will" to go ahead.

The initiative is a long-cherished one by Poland and France, which wants to go beyond EU battlegroups - temporary teams of troops from two or three EU countries ready to be sent to hot-spots at short notice - toward an EU army.

It comes after the conflict in Libya showed that the US, individual EU countries such as France and the UK, as well as Nato, pitch the EU into the background in the case of war.

Ashton drew up a hybrid EU military-humanitarian mission - Eufor Libya - but the project never got off the ground.

The US has in the past said it wants the EU to do more in managing world crises. But the group of five risk angering the UK, the EU's biggest military spender, which forcefully criticised the idea in July.

"I have made very clear that the United Kingdom will not agree to a permanent operational HQ. We will not agree to it now and we will not agree to it in the future. That is a red line," UK foreign miniser William Hague said at the time. Duplicating Nato structures is a "waste of money", he added.