"It is a just cause and it is a cause that we will succeed in winning," Mr Blair said.

He also said it would continue until Nato's demands were met in full.

His words echoed those of Nato Secretary-General Javier Solana, who spoke just a few minutes before Mr Blair took the stand.

"We will stand firm to the very end," said Mr Solana.

The BBC's Nicholas Witchell: Tony Blair told Nato it was a just war in a just cause

In London, UK Foreign Secretary Robin Cook met the head of the UN war crimes tribunal, Louise Arbour, to discuss plans to provide the tribunal with detailed military intelligence material.

Mr Cook said the UK would allow the largest ever such release of information in order to asssist war crimes investigations.

Blair describes bombing

Mr Blair began his address in Brussels by paying tribute to Nato forces out in the field, and said that troops in action "have every reason to be proud of themselves".

Mike Williams: Targets appear to be industrial zones of Nis

Outlining the previous night's bombing operations, he said that at least 13 military targets had been struck, and said that so far in the campaign, 50% of Serbian air capacity had been destroyed.

In the 27th night of bombing raids, Nato planes reportedly attacked Yugoslav communications sites and a military garrison.

Mr Blair attended this morning's operational briefing session which Nato Commander General Wesley Clark began by saying: "We had a pretty good night last night."

The official media in Yugoslavia said Nato air strikes on Monday night had killed one person and injured more than others, despite Nato's insistence that it was attacking only military targets.

The reports said houses, a tobacco factory and a building supplies plant were wrecked.

Elsewhere, a series of explosions was reported in Kosovo's main city of Pristina and near the Yugoslav capital, Belgrade. There were no details of damage or casualties.

Reinforcements expected

The Apache AH-64s can unleash Hellfire laser-guided missiles

Reports from Albania say that 24 Apache ground-attack helicopters have arrived to back up Nato forces in Albania.

Codenamed Task Force Hawk, the helicopters will be used to hit tanks and other military vehicles inside Kosovo.

They had previously been delayed by bad weather.

The US has announced an extra 500 paratroopers on their way to Albania as support for the helicopters.

Montenegro expulsions

According to Tuesday's Nato briefing, Serbian forces appear to have extended their operations against Kosovo Albanians to villages in Montenegro.

Nato spokesman Jamie Shea said it was a "new and distressing" development in the conflict over Kosovo.

Like Kosovo, Montenegro is part of the Federal Republic of Yugoslavia but has made attempts to stay out of the conflict.

UN says camps full

The UN refugee agency UNHCR declared camps in Macedonia full beyond capacity overnight on Tuesday.

The Macedonian government admitted only 400 refugees overnight, according to UN officials.

Reports say Macedonian camps ar at bursting point

The decision follows reports by the World Food Programme that an estimated 800,000 people are heading for the Albanian, Montenegrin and Macedonian borders, although numbers of crossings slowed to a trickle on Tuesday.

A UN spokesman has said that Serbian forces were forcibly preventing people from leaving Kosovo.

"It all sounds fairly ominous and we don't know to what end they're doing it," said Kris Janowski, spokesman for the UN High Commissioner for Refugees in Geneva.

Serbian reports said that 20,000 refugees had returned voluntarily to their villages near Podujevo in northern Kosovo, after being forced out by Nato bombings and separatist attacks.

• Bombs fall amid refugee fears
• Nato calls for oil embargo
• Nato: 'We may have killed refugees'
• US volunteers join Kosovo rebels
• In the belly of a B-52