Mr Blair who is at the start of a visit to see for himself the extent of the crisis in the region, also praised British troops in the former Yugoslav republic of Macedonia for their 'very important' role.

As well as increasing aid from £20m to £40m, the Prime Minister said the UK would take in more refugees.

Along with his wife, Cherie, Mr Blair crossed the barrier into no-man's land to talk with refugees from Kosovo.

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After hearing their description of their flight from the region, Mr Blair said: "I have just been talking to them about the torment they have been through, people who have seen loved ones killed, who have had their money taken from them, who have seen the most unbelievable brutality carried out across the border.

"We must redouble our commitment to these people".

Earlier, he told soldiers of the UK's 4th Armoured Brigade that their role in the Balkans would "make a huge difference to the security and the stability of the world in the 21st century".

He added: "We are determined to succeed. You are our means to succeed and we honour you and we thank you."

Paul Wood in Macedonia: Mr Blair was given a hero's welcome

Mr Blair arrived at Skopje, Macedonia at about 1300BST, for the two-day trip to Macedonia and Romania.

The visit is aimed at showing solidarity with Serbia's neighbours over their stance in the Kosovo conflict, and thanking them for coping with hundreds of thousands of refugees.

Mr Blair was accompanied by his wife Cherie, chief of defence staff, General Sir Charles Guthrie, and military advisors.

Mr Blair gave an interview to a local television station, in which he thanked the Macedonian people for their part in the crisis, and promised that the refugees would not stay in the country permanently.

Mr Blair announced support for the seven frontline states

Macedonia is in dire straights, with the refugee situation threatening to cripple an already vulnerable economy.

There is already 40% unemployment, and the country's leaders say the crisis has so far cost £32m. They also fear the influx of ethnic Albanians will upset the balance of its population, which has a significant Serb component.

Macedonia is currently hosting 180,000 Kosovo Albanian refugees - equivalent to 10% of its population, and is expecting more to flood in. Up to 11,000 arrived on a night train just before Mr Blair's visit.

Humanitarian groups and Macedonian leaders have warned that the camps cannot be run humanely if more refugees continue to arrive, and have asked other countries to do more to help.

Boost in aid

Mr Blair is expected to continue his message of support on Tuesday, in a speech to the Romanian parliament.

A Downing Street spokesman said Mr Blair will "emphasise our short-term commitment to resolving this crisis and our long-term commitment to build lasting stability in the region.

"His speech will set out the reasons why we are in this conflict and our absolute determination to see it through," the spokesman added.