“The border crossing for migrants near (Macedonian border town) Gevgelija opened early this morning, but only those migrants whose Greek registration papers show their final destination as Germany or Austria can enter,” a senior police official in Skopje told AFP.
Most of the migrants — mainly conflict refugees from Syria, Iraq and Afghanistan — had slept in heated tents operated by aid groups.
Among them are families with hundreds of children.
After Macedonia temporarily closed down the border this week, aid groups had warned that their resources had been stretched to capacity.
“If this flow continues there is no possibility for accommodation,” Antonis Rigas, head of the local Doctors Without Borders mission to the Greek side of the frontier, told AFP earlier.
“It gets very cold at night. Early this morning the temperature was minus seven Celsius (19.4 Fahrenheit),” he said.
Some 600 migrants had already spent the night on buses parked a few kilometers (miles) from the border.
Macedonia on Wednesday said it had closed the border with Greece owing to problems with Slovenian trains that had disrupted the flow of migrants moving further north.
Greek police countered that the frontier had actually shut a day earlier.
And the Slovenian rail company Slovenske Zeleznice insisted they were running services as normal.
Leading children’s charities have warned that young refugees were at serious risk from the bitterly cold Balkan weather, as figures showed 31,000 migrants had arrived in Greece already this year.
Macedonia’s plans to allow through only those who seek refuge in Austria and Germany follows similar decisions by countries further along the main migrant route -- Serbia and Croatia announced they would do the same on Wednesday.
Austria last week also signaled that it would follow neighboring Germany’s lead and begin turning back any new arrivals seeking to claim asylum in Scandinavia, after Sweden and Denmark tightened their borders.
Countries along the Balkan route earlier restricted entry only to refugees from Syria, Afghanistan and Iraq.
More than one million migrants and refugees crossed the Mediterranean Sea to Europe in 2015, nearly half of them Syrians, according to the UN refugee agency, UNHCR.
The International Organization for Migration said this week that 31,000 had arrived in Greece already this year.
S/SH