The UNHCR has offered to take over processing the queues, saying it can move 20,000 refugees per day, far more than is being managed at present.

Reports from Macedonia later on Monday said the first of the airlifts had begun, with 150 refugees flown to Turkey.

Correspondents say there is a 25 km long queue of refugees waiting at one border crossing. Another 50,000 are expected to be deposited by trains in the coming days.

Nato has begun erecting holding camps for up to 100,000 people in an attempt to relieve suffering on the border.

The BBC's Paul Wood in Skopje, Macedonia: "Growing sense of fury among the aid workers"

UNHCR spokesperson Paula Ghedini said: "We have the capacity to move all of them out in two days, it's just a matter of getting authorisation from the Macedonian authorities."

Ms Ghedini says there has been no reponse from the Macedonian government.

A BBC correspondent in Macedonia says that while criticism of the authorities has, so far, been measured, privately there is a growing sense of fury among aid workers at what is perceived as the disastrously slow movement of refugees.

UK Development Secretary Claire Short is holding talks with Macedonian officials in an attempt to speed up the processing of refugees.

Airlift

Those who have already crossed the border are being moved in convoys to the new camps, which were set up by Nato after Macedonia said it would not take any more refugees.

Clarence Mitchell reports: "They are waiting for a scale of organised help which isn't there"

The camps will provide food and medical care for the refugees, and arrange for them to be airlifted to other countries, including Germany, the UK and the US.

Some of the refugees have been given their first hot meal after being out in the open for almost a week.

The UNHCR says that one camp by the Kosovo border set up by British troops can process more than 5,000 refugees a day.

The huge logistical operation involves hundreds of cooks, engineers and medical staff to deal with the expected huge influx of refugees.

On Sunday, Nato announced plans by most of its member states to temporarily take in refugees to ease the pressure on the region.

Germany has offered to take 40,000 Kosovo Albanians, and the United States and Turkey 20,000 each. The UK says it will take several thousand refugees.

The first flights are expected to leave on Monday.

But Nato says the long-term objective is for the refugees to return home.

UK Foreign Secretary Robin Cook confirmed that the Nato campaign against Yugoslavia would continue until President Slobodan Milosevic pulled his armed forces completely out of Kosovo, and allowed refugees to return.

Missiles pound Belgrade

In a twelfth night of bombing raids on targets in Serbia and Kosovo, Nato aircraft have hit the Yugoslav Air Force headquarters and anti-aircraft command on the outskirts of the capital, Belgrade.

The BBC's Fergal Parkinson on the Kosovo-Macedonian border: "It is still a desperate sight here"

Serbian state television is also reporting attacks on an army barracks and the training school of the special police force.

A Nato spokesman said an improvement in the weather had allowed the raids to be stepped up.

The US announced it was boosting air operations with the deployment of 24 Apache helicopters and 2,000 extra troops.

Bridget Kendall reports: "Nato campaign is stepping up"

The helicopters, which can operate in all weathers, are low-flying attack aircraft used to fight ground troops and tanks. They are expected to be deployed against forces shelling Kosovo villages.

Albania bears the brunt

At least 360,000 Kosovo Albanians have poured out of Kosovo since the air strikes began on 24 March.

More than 360,000 people have fled Kosovo in less than two weeks

Albania - one of Europe's poorest countries - has born the brunt of the flood of refugee crisis. At least 226,000 have entered the country since the Nato offensive began.

They are being told they can stay in Albania until its safe to go back to Kosovo.

Some have arrived at the remote Qafa e Prushit border crossing, presenting aid agencies with the difficult task of delivering food and medical aid.

Aid workers say the Serb forces are deliberately making people flee through ever more remote crossings to hinder the aid effort.