The plan would end the current system of different countries holding the EU presidency for six months at a time.

Instead, there would be a European Commission president, elected directly by the European Parliament, and a second president selected by countries on the EU Council of member states.

We have to make sure we don't end up with the problem... of two competing power centres Jonathan Todd European Commission

Critics believe it could eventually erode the commission's influence, giving too much power to the most influential states - or could create awkward "co-habitation" conflicts, when the two presidents held different views.

But its supporters believe it could end the confusing system of a constantly-revolving presidency, and give the EU greater clout on the world stage.

Greece, which currently holds the revolving presidency, gave a lukewarm response to the plan.

Greek Prime Minister Costas Simitis said the idea of an elected Council president had previously been opposed by smaller member states.

In principle it may be that this is a solution to the existing problems, but there is still a lot of work to do Costas Simitis Greek Prime Minister

"I think it's necessary to discuss it in order to clarify what the responsibilities of the president of the Council will be, how he will co-operate with the president of the Commission and what will happen in case of differences between them," he said.

"So in principle it may be that this is a solution to the existing problems, but there is still a lot of work to do."

The Franco-German plan is a compromise between their two previously held positions - Germany traditionally favouring more power for the commission and parliament, and France being keen for EU leaders to play a greater role.

The two countries, keen to give fresh impetus to their traditionally-powerful relationship, believe the plan could help streamline European decision-making.

The proposal was agreed by French President Jacques Chirac and German Chancellor Gerhard Schroeder at a dinner in Paris on Tuesday evening.

The two presidents would be:

• A European Commission president, elected by parliament instead of member state's leaders, running the EU's daily affairs, as at present
• A de-facto EU president - appointed by EU leaders - to speak on EU policy and provide leadership, to serve for a maximum two-and-a-half year term.

A spokesman for the European Commission, Jonathan Todd, warned that internal friction could result from a dual presidency.

"We have to make sure we don't end up with the problem... of two competing power centres," he said.

Most opposition is expected to come from smaller countries including the Netherlands, Belgium and Finland, who believe the bigger nations will become more powerful than ever within the EU.

Danish Prime Minister Anders Fogh Rasmussen said one possible solution would be for the EU president to be chosen from countries grouped into small, medium and large states, to ensure that smaller nations did not get overlooked.

It was very, very difficult to find a compromise Joschka Fischer German FM

In Germany, pro-federalist Foreign Minister Joschka Fischer said he would have preferred a single president to lead the commission and the council.

"It was very, very difficult to find a compromise," Mr Fischer said.

Giovanni Grevi of the European Policy Centre said the European Commission could find itself being more and more marginalised.

Correspondents say the plan could have a decisive effect on efforts by the EU's Convention on the Future of Europe to prepare a constitutional treaty for the EU.

Full details of the proposals have not been released, but they will be passed to the convention, run by Frenchman Valery Giscard d'Estaing.