(Click here to see a map of Nato's overnight strikes)

Serbian shelling on the Albanian border with Kosovo was reported to be the "heaviest so far" on Friday, according to international observers.

Four people along a 20km stretch of the border were injured, said a spokesperson for the the Organisation for Security and Co-operation in Europe (OSCE).

Meeting with Serbs

Nato officials are due to hold a meeting with Serbian military officials on the Kosovo border on Saturday morning.

The BBC's Bridget Kendall: "The deal isn't done yet"

They are expected to discuss how Serbian troops can leave Kosovo under the timetable laid out in the peace proposal accepted by Belgrade on Thursday.

The timetable calls for all 40,000 troops to be out within seven days.

Clinton expresses hope

In a speech at the White House on Friday, US President Bill Clinton expressed his gratitude to the envoys whose efforts led to the planned talks.

He hoped the talks would progress effectively, but urged caution in dealing with the Yugoslav President Slobodan Milosevic.

President Bill Clinton: "Military efforts will continue until we see Serb forces withdraw"

"Our experience in the Balkans teaches us that true peace can only come when progress in discussions is followed by progress on the ground," said President Clinton.

US peacekeeping troops are preparing to move into Kosovo "within days", if the promised Serb withdrawal takes place, according to Washington.

"There will be a military-to-military relationship established ... in the event that there is intent to fully comply with this," US Defence Secretary William Cohen told a news conference at the Pentagon on Friday.

The BBC's Tom Carver in Washington: "The Pentagon has to be convinced"

According to the BBC's correspondent in Washington, Richard Lister, there are still major differences with Moscow over what part Russian troops will play in Kosovo.

Milosevic under pressure

Meanwhile, President Milosevic is coming under increasing international pressure to step down.

Germany, the UK and France made it clear at the European Union summit that Serbia will get no international aid as long as he remains in power.

And the chief prosecutor at the international war crimes tribunal in The Hague, Louise Arbour, said there was no question of granting President Milosevic immunity now that he has accepted the peace plan.

International force prepares

Preparations for assembling a peacekeeping force are continuing, with Nato Secretary-General Javier Solana saying it would take only a "very short time" to deploy the estimated 50,000 troops of the Kosovo force.

The UK announced 4,000 British troops would leave at short notice for the Balkans.

The Clinton administration has also intensified planning for deploying international peacekeepers, returning refugees and reconstructing Yugoslavia.

Under the terms of the peace agreement a security force "with essential Nato participation" will be deployed once Serb forces withdraw.

European Union leaders are working on plans to help the hundreds of thousands of Kosovo Albanians return to their homes.

Germany's Chancellor Gerhard Schröder said they had agreed to do everything possible to build up the momentum towards peace, and to look after the refugees in the coming winter.

• Milosevic in Nato's sights
• Full text of the peace document
• Refugees sceptical about peace
• What the Serbs have been told
• Q & A: Did the Serbs lose out?
• Analysis: The limits of air power

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