Chaos ensued as thousands of people pushed through the Macedonian border as police allowed a small group to enter the country. Security forces have strengthened barricades and added a second layer of barbed wire.
Thousands of migrants broke police lines at the Macedonian border with Greece on Saturday, despite a blockade preventing them from entering the Balkan country, news agencies reported.
The rush happened as police attempted to allow a small group of migrants with small children to pass, when crowds at the back rushed towards the shielded police wall.
There were no immediate reports on the number of injuries.
Around 2,000 people - including women and children - had slept outside overnight in cold and wet conditions, despite calls by the United Nations refugee agency (UNHCR) for the border to be reopened.
Early on Saturday, groups of "vulnerable" families with children were permitted over the border, near the town of Gevgelija, where they headed to a nearby railway station, reported The Associated Press. From there, they boarded trains to Serbia from where they could travel further north to EU-member Hungary.
On Thursday, Macedonia declared a state of emergency on its frontier as it struggled to deal with the huge influx of refugees, mostly escaping war in Syria, travelling through the country towards the EU's open-border Schengen zone.
Some 45,000 people crossed into the country over the past two months.
Since its border was sealed, hundreds of new refugees have entered the no-mans-land between Greece and Macedonia, amid fears that the closure of the frontier will create a major bottleneck.
Overnight, thousands of migrants used makeshift materials to attempt to shelter from the cold and rain.
"It's really cold here," said 30-year-old Faroq Awais, from Pakistan, waiting for a train in Gevgelija. "Last night it was raining and we couldn't go anywhere inside. We were sleeping against the walls of a building but it didn't help."
Refugees charged more
Macedonia's state railway put on two extra trains - in addition to the three scheduled services - to carry the extra passengers and almost doubled the price of a ticket to the Serbian border.
On Friday, police used stun grenades and tear gas to drive back the crowds in an attempt to prevent a repeat of the chaotic scenes seen last week at Gevgelija railway station, when crowds stormed the trains.
Macedonian police, along with military support, had put up new security barricades along the Greek border on Saturday to prevent migrants from pushing through.
According to A1TV, a second line of barbed wire has been stretched between Macedonian territory and the stranded refugees.
Most of the migrants hope to apply for asylum in Germany and other wealthy EU nations, which are seeing unprecedented numbers seeking residence.
mm/se (AP, AFP, dpa)