The big powers are bringing renewed pressure on the Serbs and ethnic Albanians this weekend as the Kosovo peace conference in France reaches what is expected to be its mid-point.

The American Secretary of State, Madeleine Albright's arrival in Paris this weekend will also involve meeting foreign ministers from western Europe and Russia.

Hard talking is going on between the Russians and the West on the military side of the proposed peace agreement.

Conference sources say the military annex to the peace agreement, drawn up by Western governments, was passed to the Russians on Thursday.

One diplomat said they had to sell it to Moscow - that was now the centre of the discussions.

Serbian nationalists protest outside the talks

The Russians do not want the international force which would be sent into Kosovo to implement any peace deal to be an explicitly Nato operation.

They would like it to be run by the Organisation for Security and Cooperation in Europe, the OSCE, of which they're members.

But the Americans in particular insist that only Nato could run such an operation. The draft text does not use the word Nato.

The military and security aspects of the proposed agreement are also the most sensitive as far as the Serbs and ethnic Albanians are concerned.

The Serbs will be required to withdraw most of their forces from Kosovo and both they and the guerrillas of the Kosovo Liberation Army, the KLA, will have to put their heavy weapons under international supervision.

Albright: due at talks

When Mrs Albright visits Rambouillet on Sunday she is expected to become involved in all these issues.

The Contact Group of five Western powers and Russia is almost certain to extend the talks for a second and final week.

Only repeated and intense pressure applied from outside has a chance of security an agreement.

Nato military preparations are designed to help build momentum and convince the Serbs, in particular, that they have to make concessions.