As the EU held talks on its first constitution on Friday, French Foreign Minister Dominique de Villepin said Western Europe’s three biggest powers would submit proposals to their conference partners that night.
"This is a key issue. We can't have a Europe without defence," de Villepin separately told France-Info radio from Naples.
A British Foreign Office spokesman confirmed several ideas had been drafted and indicated there would be further discussions with the rest of the EU and the US.
"Any EU operations planning capability has to be compatible with NATO," the official added.
Agreement by the EU's Big Three would significantly ease the path to finalising the constitution's text on the bloc's nascent common defence policy.
Senior officials from the trio met in Berlin on Wednesday to discuss the military planning office ahead of the two-day Naples meeting, including how it would cooperate with NATO, the Financial Times said.
France's Dominique de Villepin
says proposals will be discussed
The constitution proposes three new areas for the EU to build its military policy - through "structured cooperation", "mutual defence" and "autonomy" for planning operations separate to NATO.
But Britain has sought to ease US concerns about the plans by saying an EU planning arm will never rival NATO, insisting the alliance forms the bedrock of Europe's defence.
Indeed, London says its right to control its own defence policy is one of the "red lines" it will not allow the new EU constitution to cross. The EU facility would only plan for operations that NATO does not want to be involved in, Britain says.
French newspaper Le Monde said on Friday the military planning facility would be based in the EU district of Brussels, in the same building as the bloc's military and police staff, and comprise about 130 staff officers, it said.
There is broad agreement among member states that the EU needs to bolster its military planning to deal with crises both near and far.
The 15-state Union, which is preparing to take in 10 mostly ex-Soviet new members next year, launched its first-ever peacekeeping operation, in Macedonia, in March.
It has also sent troops under French command to the Democratic Republic of Congo and is working on plans to succeed NATO peacekeepers in Bosnia.
And in another advance, EU defence ministers agreed last week to set up an arms procurement agency next year to streamline and improve the bloc's military muscle.