Hundreds of migrants have rushed at Macedonian border forces in an attempt to enter the country from Greece.
The BBC’s James Reynolds, at the scene, says dozens of families have managed to get through but many more people are being held back.
On Thursday, Macedonia declared a state of emergency in two border regions to cope with an influx of migrants, many from the Middle East.
The migrants are trying to reach northern European Union members.
Macedonian police earlier fired tear gas to disperse the migrants. Razor wire has been rolled across the frontier to prevent people from entering.
Some 44,000 people have reportedly travelled through the country in the past two months, meeting little border resistance.
Our correspondent says hundreds of migrants crushed their way towards the border’s security forces on Friday afternoon.
A number of people reportedly fainted and were treated by aid workers.
The interior ministry on Friday said it would allow a “limited number of illegal migrants in vulnerable categories to enter Macedonia and they may be provided aid in accordance with the state’s capacities”. It gave no further details.
Police have issued temporary transit documents to 181 migrants in the past 24 hours.
Spokesman Ivo Kotevski told Reuters: “We are allowing entry to a number that matches our capacity to transport them or to give them appropriate medical care and treatment.”
One 18-year-old Syrian man said he was able to cross overnight into Macedonia, but others were caught and driven back.
“I ran fast and escaped,” he said. “They got my brother and most of the others and sent them back to Greece.”
In recent weeks there have been chaotic scenes at Gevgelija station, with migrants trying to clamber on board packed trains bound north.
As well as Gevgelija, Macedonia declared a state of emergency in northern Kumanovo, where migrants attempt to travel on to Serbia, the next stop before entering Hungary, which is part of the EU.
Greece itself has seen almost 160,000 people landing on its shores since January, the UN estimates, with 50,000 arriving in the past month alone.
There were fears that by effectively shutting off its borders, Macedonia would create a backlog of migrants at its frontiers.
Those trying to reach northern and western Europe come from the Middle East, Africa and Asia, but many arriving in Macedonia are escaping the conflict in Syria.
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