The Belgrade authorities and the Kosovo Liberation Army (KLA) have been told by Russia and five Western powers to negotiate an agreement on autonomy within three weeks or face unspecified military action.

But the situation on the ground in Kosovo remains tense with the discovery of the bodies of 24 ethnic Albanian men in the western village of Rogovo.

The BBC's Paul Wood: "There may be another war of nerves"

The dead, who included three men wearing KLA uniforms, were apparently killed by Serbian security forces following an ambush which took the life of a Serb policeman.

'Bomb to avenge KLA deaths'

Later a bomb exploded near a cafe frequented by Serbs in the capital, Pristina, injuring seven people. The police said they found a message at the scene saying the bomb was to avenge KLA deaths.

The International Contact Group of foreign ministers, becoming increasingly exasperated by the continued violence in Kosovo, met in London on Friday and came up with the ultimatum, which has been formally backed by the UN Security Council.

A Serb policeman inspects the damage in a Pristina cafe after a bomb went off

Belgrade has been ordered to offer Kosovo "substantial autonomy" but the Contact Group statement falls short of the KLA's demands for independence.

Yugoslav leaders in Belgrade and the moderate ethnic Albanian leadership in Kosovo have promised to attend talks. But a representative of the KLA said there could be no talks while Serbian repression continued.

Mr Cook, as the Contact Group's chairman, summoned both sides in the Kosovo conflict to meet for talks within a week.

Cook to meet Milosevic

He is expected to meet Serbia's President Slobodan Milosevic and moderate Kosovo Albanian leader Ibrahim Rugova and will impress on them the need for agreement.

OSCE spokesman Sandy Blyth: "This is another incident of a shocking nature"

The Rogovo incident is bound to heighten tension in the region but OSCE spokesman Sandy Blyth has refused to call it a massacre.

He said: "There was a shooting at around dawn when one police officer was killed.

"In the subsequent police operation 24 Albanians were killed. Three were in KLA uniform and the rest were in civilian clothes."

Threat of force

A statement after the London talks said both the Yugoslav authorities and ethnic Albanian leaders would be held accountable if the negotiations failed. Correspondents say the wording clearly carries the threat of Nato military action.

The UK, France and Germany have underpinned Nato's warning by saying they are prepared to send ground troops to Kosovo to enforce a negotiated settlement.

The BBC's Washington Correspondent Richard Lister: "Mr Clinton said the time for denial and delay was past"

But it remains unclear whether the US would support such a move. Ms Albright said the Clinton administration would consult Congress about a possible role for US troops in enforcing an interim peace deal.

President Clinton said the US and its allies were united behind the international political process, and were "ready to back that strategy with the threat of force".

Proposals for peace

Ethnic Albanian women and children leave the village of Donje Ljupce after fighting

The Contact Group paper proposes "a self-governing Kosovo with free and fair elections supervised by the OSCE and with control over their own police and internal security", said Mr Cook.

Mixed response

The Contact Group's proposals have received a mixed welcome from the two sides themselves.

Yugoslav President Slobodan Milosevic indirectly rejected an international conference on Kosovo, calling instead for direct talks between all ethnic communities in the province.

Earlier Serbian Deputy Information Minister Miodrag Popovic welcomed the talks, but said Serbia's forces could not observe a ceasefire - a precondition set by ethnic Albanian leaders.

"We can't speak of any ceasefire because we consider the KLA a terrorist organisation."

Mr Rugova said he would send representatives to the peace talks in France, but was not yet sure if he himself would go.

Robin Cook: "A very tight timetable"

But he warned: "We cannot move ahead with negotiations ... that would eventually serve as a cover-up for the massacres and the killings that Belgrade has been committing."