The damage inflicted by cruise missiles and bombers was severe, but precisely targeted, they said.

The raids struck at Serb air defences, power stations and grids, arms factories, airports, army barracks, police stations, and command and control centres across Yugoslavia.

Nato's Supreme Allied Commander in Europe, General Wesley Clark, told journalists at Nato headquarters that all allied planes returned safely.

Barracks in the Kosovo capital Pristina go up in flames

"We're going to systematically and progressively attack, disrupt, degrade, devastate and ultimately, unless President Milosevic complies with the demands of the international community, we're going to destroy his forces and their facilities and support," General Clark said.

Every effort was being made to avoid civilian deaths and collateral damage, he said.

Kate Adie watched the attack begin at sunset from on board the USS Gonzalez

The Secretary-General of Nato, Javier Solana, described the attacks as a success.

General Clark did not name any specific targets, but insisted that "downtown Belgrade" was not hit.

But Yugoslav authorities said

• ten people were killed
• 38 wounded
• some civilian targets had been hit, but the damage suffered was minimal.

Nicholas Witchell reports on "scenes reminiscent of World War II"

The Yugoslav Information Minister, Goran Matic, told the US television channel, CNN, that at least 10 people - "not soldiers but civilians" - were killed during the first night of bombing.

Lieutenant General Nebojsa Pavkovic, the commander of Yugoslav troops in Kosovo, said 40 targets were hit in three hours, including five airports, five barracks, and communications and command positions.

Air defence system targeted

The Nato attack began with both sea- and air-launched cruise missiles. Many of them were aimed at the Serbs' air defence system, which includes up to 1,000 Russian-designed surface-to-air missiles with advanced guidance systems.

US B-52 bombers, F-16 fighter-bombers and F-117 stealth fighters, as well as Canadian F-18s and other Nato aircraft from 11 countries, were among the 400-plane force.

The Pentagon said no Nato aircraft were lost. Nato noted that the Serbs did not use their anti-aircraft radar.

Serb civilians huddle together as the bombings begin

At least one factory which makes parts for air defence systems was targeted, a US official said, speaking anonymously.

The Associated Press agency reported that in the Belgrade area, Nato struck near a power station, and the Batajnica military airport, the main Serbian airbase, 10 miles (16 km) west of the Serb capital.

Four missiles also struck an aircraft plant at Pancevo, six miles (9km) north of Belgrade, destroying several small planes.

The central Serb town of Kragujevac, a major military-industrial centre, was plunged into darkness after a heavy explosion, the private news agency Beta reported.

Nato 'taking care'

General Sir Charles Guthrie, UK Chief of the Defence Staff, said an ammunitions storage facility was hit by six RAF Harriers.

He said: "We do not yet have any detailed imagery of the targets and it will probably take some time for Nato to conduct a full battle damage assessment exercise."

Two B-2 stealth bombers, each carrying 16 satellite-guided 1-ton bombs in the first combat test of the bat-winged plane, delivered some of the heaviest hits, including on command bunkers and air defences, a senior US defence official said.

US Defence Secretary William Cohen said Nato planners picked targets "with great care."

Damage assessment

He said Nato was attacking "the military infrastructure" that Serbian forces, directed by Yugoslav President Slobodan Milosevic, were using "to repress and kill innocent people".

An official Nato bomb damage assessment will come from satellite photos and surveillance planes, Pentagon officials said. Camera footage from warplanes and pilots also will provide details.

In the Kosovo capital of Pristina, a power grid was hit, leaving the city's 200,000 residents in darkness, and several heavy blasts came from around the nearby Slatina airport, the official Tanjug news agency reported.

The most visible damage was to a row of Albanian cafes, stores and a private medical clinic which, say correspondents, had been gutted either by bombs or grenade attacks.

Witnesses said the headquarters of the moderate ethnic Albanian leader Ibrahim Rugova had been burnt down.

In neighbouring Montenegro, which with Serbia forms Yugoslavia, an army military barracks in Danilovgrad burst into flames after being hit. One soldier was reported killed and three wounded.

Gen Clark denied that a pharmaceutical plant had been bombed.