Yugoslav media said Nato bombs had pounded transport, defence and telecommunications targets within Serbia and Kosovo, in keeping with the recent pattern of heavy attacks.

The action came as the Australian Government said it planned to appeal against Belgrade's "incomprehensible" decision to jail three employees of an Australian aid agency on spying charges.

In the US, an international aid agency said it planned to begin dropping food supplies to refugees within Kosovo in the next few days.

Major explosions

Residents in Belgrade reported major explosions near a radar station in the district of Strazevica and a TV transmitter in the Pirot area of the Serb capital late on Saturday.

The BBC's Jim Fish: The severity of the sentences has shocked many people

Kosovo's capital, Pristina, and the heavily industrialised Serb city of Nis were also understood to have been hit.

The official Yugoslav news agency Tanjug said a number of civilians were killed and wounded when Nato hit three broadcasting transmitters, two bridges, a tunnel and a barracks.

The bombing continued shortly after Russia's Balkans envoy, Viktor Chernomyrdin, returned to Moscow on Friday after another peace mission to Belgrade.

Mr Chernomyrdin said he was "very satisfied" with the talks he had held with Yugoslav President Slobodan Milosevic, but failed to reveal what had been discussed.

Following his visit, Yugoslavia reiterated its "general acceptance" of the principles drawn up for a diplomatic settlement by Russia and the seven other G8 nations.

French Prime Minister Jacques Chirac and German Chancellor Gerhard Schröder said the G8 countries should meet again to to ask Mr Chernomyrdin if he had made any progress.

Nato Secretary General Javier Solana described the suggestion as a "good initiative".

Despite this latest move, the United States has reportedly ordered a further 68 warplanes into the region, bringing the total number of Nato aircraft involved in Kosovo to about 1,100.

Australian anger

A man examines a downed aerial

Meanwhile, Australia responded angrily to the jailing on charges of espionage of two of its citizens and a Yugoslav national who worked for the aid charity Care.

Plans for a formal appeal are already being drawn up. Any appeal must be submitted within three days of the conviction.

Australia's Foreign Minister, Alexander Downer, described the verdict as "deeply distressing".

Care Australia spokesman Brian Doolan said the verdict could have a serious impact on aid operations in and around Kosovo.

"That means, of course, that there are some 50,000 Serbian refugees who are currently reliant on Care for the provision of food and fuel who may no longer be able to access that food and fuel through Care," he said.

(Click here to see a map of latest Nato strikes)

Australians Steven Pratt and Peter Wallace were handed 12 and four-year terms respectively, while local employee, Branko Jelen, received a six-year term.

Steven Pratt pictured with his wife

An international aid organisation has announced that it is to begin dropping food to displaced people inside Kosovo within the next few days.

The International Rescue Committee announced in New York that it wants to fly two chartered Russian planes from Italy and drop enough food to feed 15,000 people a day.

Nato has resisted pressure to make food drops for the thousands of people living in the hills in Kosovo because of the risk that its planes would be shot down.

So far, the Yugoslav government has not given official permission for the air drops, and a foreign ministry spokesman said they would be viewed as a hostile act.

• Belgrade diplomacy leaves Nato unmoved
• Text of Yugoslav statement
• Aid group plans Kosovo air drops
• Nato prepares for 'Phase Three'
• KLA go on the offensive

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