But, apologising for the loss of life, Nato spokesman Jamie Shea said that the "tragic accident" would not undermine the alliance's resolve to bring an end to Yugoslav President Slobodan Milosevic's ethnic cleansing of the province.

"Sometimes one has to risk the lives of the few to save the lives of the many," said Mr Shea.

Nato's admission came the day after more than 60 refugees were reported to have been killed in at least two attacks in the south of the province.

At first the Pentagon had suggested that Serb forces had attacked convoys of refugees - a statement it later withdrew.

'Bombed in good faith'

Hear the pilot talk through the bombing raid

Speaking to reporters at Nato headquarters in Brussels, Mr Shea said: "A Nato pilot was operating over western Kosovo and saw villages being burnt.

"This is an area where the Yugoslav special forces have been conducting ethnic cleansing in the last few days."

Mr Shea said the F-16 fighter pilot identified vehicles moving on the main road between Prizren and Djakovica, a route described by Nato as a key military supply corridor.

"The pilot attacked what he believed to be military vehicles," said Mr Shea. "He dropped his bomb in good faith, as you would expect of a trained pilot from a democratic country.

"The pilot reported at that time that he had attacked a military convoy.

"The bomb destroyed the lead vehicle which we now believe to have been a civilian vehicle."

Mr Shea said that despite the accident, Nato was taking more measures than any other force in combat history to minimise harm to civilians.

Sadaf Maruf: "Nato has stressed it was aiming at military targets"

But he stressed that even with the best military hardware available, there could never be a guarantee that there would not be tragic accidents.

And he added: "The refugees want Nato to continue its operations. And continue we will.

"One tragic accident cannot and will not undermine our conviction that our cause is a just one."

Pilot explains attack

In a recorded debriefing, the unidentified pilot explained how he became convinced that the vehicles he attacked were Yugoslav forces systematically burning house after house.

An eyewitnesses describes the attack

"The picture that I'm getting is that MUP (Yugoslav) forces are methodically woking from the north to the south and forcing the Kosovo Albanians from their villages," he tells the interviewer.

Operating with a wing-man, the F-16 pilot made several passes over a convoy near Djakovica.

After identifying more than 60 vehicles, he spots a further three "uniform shaped dark green vehicles" stopping near a home.

Fearing an attack on civilians, the pilot made two further passes below the cloud line.

He "eyeballed" and then identified the vehicles with targeting equipment before bombing.

Cook denounces 'hypocrisy'

TV reports: Serb media have accused Nato of murder

UK Foreign Secretary Robin Cook accused the Yugoslav authorities of hypocrisy.

"How dare they now produce crocodile tears for people killed in the conflict for which they are responsible," he said.

Marko Gasic, spokesman for the Serb Information Exchange, told the BBC that the convoy had been returning to the town of Djakovica when it was attacked twice by Nato bombers.

Bombing intensifies

During a night of clear skies, Yugoslavia was subjected to one of the heaviest air strikes since Nato raids began three weeks ago.

(Click here for a map showing Nato's latest strikes).

Up to six powerful explosions shook the capital, Belgrade, shattering windows and tearing doors from their frames.

John Simpson in Belgrade: It has played entirely into President Milosevic's hands

Serbian media said army barracks at Racovica about 8km from the city centre had been hit, and power supplies to the region cut.

Nato air strikes destroyed two bridges in central and southern Serbia, one of them leading to the Kosovo capital of Pristina.

Pristina was also reported to be under heavy bombardment. Two transmitters were hit, cutting programmes of the state-run television.

• Cook damns Belgrade's 'crocodile tears'
• German peace plan fails to enthuse
• Fog of war shrouds refugee deaths
• KLA strongholds under attack
• Images of the refugee attack