But the alliance said it had to wait for battle assessments before it could confirm whether the bomb hit the hospital.

BBC Belgrade Correspondent Mike Williams, who visited the scene, said parts of the clinic had been reduced to rubble.

BBC World Affairs Editor John Simpson: "This bomb was the end of a two week lull in Belgrade"

Spokesman Jamie Shea said: "One laser bomb failed to guide correctly. We can confirm that it struck the base of the building about 1,500ft from the centre of the target area."

He added Nato is gathering increasing evidence that Serbs are become "war-weary".

Italy has said there should be a bombing pause if a document can be drafted for discussion by the United Nations Security Council.

Children's ward

John Simpson in Belgrade: "The missile trashed the whole building"

Serbian television broadcast footage showing hospital beds overturned and covered in rubble, in what appeared to be a children's ward.

The BBC's Paul Reynolds: "The perception in US media is that Britain is more forward thinking than the USA"

The US and UK have apologised for the damage, which Sweden has called "unacceptable".

Other overnight Nato attacks included targets some 20km southwest of Belgrade: a chemical plant at Baric, a large power station at Obrenovac which serves the capital and large parts of the rest of Serbia, and a water purification station in the town of Makis.

(Click here to see a map of the most recent Nato strikes)

Spokesman Mr Shea said two battalions had returned to their homes in Krusevac and Aleksandrovac after hearing radio reports of anti-war demonstrations in the towns.

He said some young men in southern Serbia, where more people are being conscripted into the army, were moving to Belgrade in an attempt to avoid the draft.

Mr Shea added: "It's too early to say whether [the desertion] was an isolated incident or part of a trend.

The BBC's Janet Barrie: "A gulf is building up over who should make up the peace keeping force"

The former mayor of Belgrade Zoran Djindjic told the BBC that Serb military police have blocked access roads to the town of Krusevac because of the anti-war protests.

He said: "It is not possible to go to the cities. It's a real crisis."

Draft plan

Dedinje army barracks suffered heavy damage

Russia's Balkan envoy, Viktor Chernomyrdin, is briefing his US counterpart and the Finnish president, his contact point with the European Union, on his negotaiations in Yugoslavia.

Mr Chernomyrdin spent seven hours with Yugoslav President Slobodan Milosevic discussing a draft peace plan proposed by the G8 group of nations, made up of Russia and the seven top industrialised countries.

Mr Chernomyrdin, who said there had been a "stride forward" in the diplomatic efforts to find peace, will resume talks in Belgrade on Monday.

BBC Moscow Correspondent Andrew Harding: "Positive spin not matched with concrete progress"

That would appear to fall short of one of the Western conditions for halting the eight-week bombing campaign - an unequivocal acceptance of the international plan.

Security Council

The G8 is also working on a resolution to be discussed by the UN Security Council.

BBC Diplomatic Correspondent Barnaby Mason: "Serious and sustained effort"

G8 officials will meet again on Friday to continue trying to draft the much-delayed resolution for a political solution.

The German representative said problems remain on the composition of an international military force for Kosovo, and the sequence of events leading to its deployment.

The BBC's Nick Childs: "Nato can still not confirm what happened"

The two countries are reported to be divided over whether to pursue a more aggressive approach to Kosovo, including the deployment of ground forces.

Mr Cook will hold a number of joint TV appearances with US Secretary of State Madeleine Albright, and he said: "I hope that will rebut some of the speculation about splits or lack of resolve."

• 'No closer allies' than UK and US
• 'Desertions' hit Serb forces
• Fighting for a foreign land
• US produces 'proof' of massacre