Securing agreement on the final status of Kosovo, Serbia's breakaway province, is a key test of the European Union's foreign and security policy, the foreign ministers of Britain and France said on Thursday.

Serbia had to present proposals acceptable to Kosovo's ethnic Albanian majority if Belgrade was to continue to oppose Kosovo independence, France's Bernard Kouchner and his British counterpart David Miliband said in a joint opinion piece.

"Kosovo will be a major test of our common foreign and security policy," they wrote in an article published by the Le Monde newspaper.

"We have to show that, despite our differences, despite possible difficulties within the (U.N.) Security Council, we are ready to stand together to ensure stability in Kosovo and allow the European Union to play the role that comes to it naturally."

Leaders of Kosovo's ethnic Albanian majority have vowed to declare independence if a new set of last-ditch talks with Belgrade fail to produce an agreement by a Dec. 10 deadline.

The issue will dominate talks in the Portuguese town of Viana do Castelo on Friday where ministers will be briefed by Wolfgang Ischinger, the German EU mediator in the negotiations who has said that chances of a deal are slim.

The EU plans to launch an 1,850-strong rule of law mission, the largest in its history, that would take over law enforcement and supervisory duties from the United Nations.

But a split in the EU over Kosovo recognition could scupper the plan, and Kouchner and Miliband said the European Union should not shirk its responsibilities over Kosovo.

U.N. mediator Martti Ahtisaari has proposed independence for Kosovo under EU supervision, an outcome resisted by Serbia, whose stance is backed by U.N. veto-holder Russia.

Kouchner and Miliband said the ball was now in Serbia's court: "If Belgrade persists in finding Mr Ahtisaari's conclusions unacceptable, it is up to it to propose alternatives that are likely to be accepted in Kosovo.

"As for Pristina, it has to reflect on the ways of convincing Serbia and the Serbs of Kosovo of its attachment to a multi-ethnic Kosovo, shorn of all discrimination," they wrote, referring to the province's Albanian-majority leadership.

"If no agreement is possible, the proposals of Mr Ahtisaari remain, in our view, the best way to advance. For one thing is certain -- the status quo is not a solution."