Click here for a map showing the latest Nato strikes on Yugoslavia

European Union interior ministers have rejected proposals for a mass evacuation of Kosovo Albanians to western Europe.

Instead they agreed to give priority to helping refugees from Kosovo in neighbouring countries.

The ministers, meeting in Luxembourg after days of confusion over policy on the issue, said that to fly the refugees to other countries would send the wrong signal to the Yugoslav government, which they blame for the exodus.

The decision came as Nato took its bombing campaign in Yugoslavia into a third week.

Two big explosions were heard in central Belgrade near the army headquarters, and local sources say a judicial building was hit.

US officials reported that an unmanned reconnaissance plane had crashed over Yugoslavia.

The BBC's Jon Leyne reports on the latest attacks on Belgrade

Earlier, the Serbs acted to stop the flow of refugees out of Kosovo; two main border points between Kosovo and Albania were closed.

Serbian police have also apparently told queues of people, who had been waiting without food on the Kosovo side of the border crossing at Blace in Macedonia, to go home.

Nato and the UN have expressed fears for the refugees trapped on the Kosovo side of the border.

In Pristina, Kosovo's regional capital, BBC World Affairs Editor John Simpson reports the streets are deserted other than by roaming packs of dogs, armed paramilitaries and a few elderly people.

John Simpson: "City is a shell of its former self"

Serb officials told the visiting party of journalists that 150,000 people remained in the city but were hiding in bomb shelters. Our correspondent said there was no sign of that.

The military alliance has been targeting Serbian forces on the ground for the first time.

Serbian armoured columns in Kosovo were hit in what Air Commodore David Wilby described as Nato's "first major breakthrough against armoured forces in the field".

Drini: "There is no ceasefire"

A Kosovo Liberation Army (KLA) spokesman, who is in the province, told BBC World TV that Nato strikes on Serb armoured had been "very efficient".

But the spokesman, known only as Drini, also said the ceasefire promise made by the Yugoslav and Serbian Governments had not been kept and that civilians continued to be targeted by Serb forces.

Fears for refugees

Nato spokesman Jamie Shea said the alliance was alarmed by the border closures.

"It is one thing to push refugees over borders where the international community is increasingly ready to deal with them in a humane way.

"It is quite another to push them back into a wasteland where there is no food, very little water, very little medical supplies and where everything has been looted."

He also said Nato suspected there are three mass graves in Kosovo, and estimated that 50 villages in the province had been torched in the past four days.

Mr Shea said Nato had put five demands to President Slobodan Milosevic and if he agreed to all of them the alliance would stop its air operations.

A spokesman for the UN refugee agency (UNHCR) Jacques Franquin, said: " I am very worried. If someone wants to flee his country because he feels persecuted, he should have the right to do that.

"We would like to know what is happening to these people."

'Missing' refugees in Albania

Almost 300,000 refugees have crossed into Albania since the conflict began, placing considerable strain on local resources and aid agencies.

Ben Brown reports: "100's of buses moved thousands of people"

Up to 20,000 more refugees, who apparently vanished overnight from Macedonia, have been traced to southern Albania.

They were taken from a makeshift camp at Blace, on the Kosovo-Macedonia border, to Albania by Macedonian riot police.

The BBC's Richard Myron says a sole refugee crossed the Albanian-Serbian border at Morina on Wednesday. The refugee reported that vehicles with people fleeing towards Albania were empty. It was unclear where these people had gone to.

EU gives more funding

At their Luxembourg meeting, the European interior ministers agreed it was necessary to keep the refugees as close as possible to their homeland.

Europe Political Correspondent Jonathan Beale: "Helping countries on the Kosovo borders"

A statement issued after the meeting said: "Long-term admission of Kosovars to countries outside the region ... would consolidate their displacement."

Correspondents say that Britain and France successfully argued against calls from Germany and Sweden to set national quotas of refugees to be taken in by member states.

Brian Hanrahan reports; A "solid basis of public opinion for Nato to conitnue"

The EU has already agreed a $270m aid package, much of it aimed at helping Albania and Macedonia.

And Albania has also offered to take in an extra 100,000 Kosovo Albanian refugees from Macedonia.

Signs of genocide

UN Secretary-General Kofi Annan said he saw signs that Serbian authorities were committing genocide in Kosovo.

Heaps of rubbish left at the encampment

The US State Department spokesman, James Rubin, has named Yugoslav commanders whose forces were believed to be conducting war crimes or crimes against humanity.

Mr Rubin said he was naming the officers "as a warning that the world is watching".

Meanwhile, Yugoslav President Slobodan Milosevic has reportedly offered to hand back three American soldiers through Cyprus as a gesture of goodwill.

The speaker of the Cypriot parliament, Spyros Kyprianou, said he will travel to Belgrade on Thursday in an effort to secure the release of soldiers captured by Yugoslav forces last week.

Mr Kyprianou said he had been in negotiations with President Milosevic, who was ready to hand over the soldiers as long as certain conditions were met.

But Nato has said the soldiers' release must be unconditional.

The UNHCR says the number of people who had fled Kosovo since 24 March, when Nato began bombing Yugoslavia, is now more than 600,000.