Helpless to stem the flow, Croatian police rounded them up at the Tovarnik railway station on the Croatian side of the border, where several thousand had spent the night under open skies. Some kept travelling, and reached Slovenia overnight.

Migrants have been streaming into Croatia for two days, their path to western Europe via Hungary blocked by a metal fence, the threat of imprisonment and riot police who fired teargas and water cannon on Wednesday to drive back stone-throwing men.

Hundreds evaded Croatian police, trekked through fields and reached the border with Slovenia by train Yesterday, part of a desperate and determined march westwards that is dividing Europe.

Only the main Bajakovo crossing, on the highway between Belgrade and Zagreb, appeared to be open to traffic today, while Slovenia stopped all rail traffic on the main line from Croatia.

Around 150 migrants spent hours overnight stranded at the Dobova railway station on Slovenia's side of the border. Police first said they would be sent back, but then the train proceeded to the town of Postojna, some 50 km (30 miles) southwest of the capital Ljubljana, where there is a refugee centre.

Slovenia, which unlike Croatia, is a member of Europe's Schengen zone of border-free travel, said it had turned back roughly another 100 who tried to cross from Croatia under cover of night.

The two former Yugoslav republics suddenly find themselves on the path of a huge migration of people westwards from war and poverty in the Middle East, Africa and Asia, the scale of which has sowed discord and recrimination in the European Union.

On Wednesday, the EU called an emergency summit for next week in a fresh bid to overcome disarray in the 28 nation bloc.

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