ATHENS/IDOMENI (Reuters) - Greece moved to slow the flow of migrants from its islands to the mainland on Friday as thousands of homeless refugees were trapped in the country by border limits imposed along a Balkan route to richer nations in northern Europe.

From its northern frontier with Macedonia to its port of Piraeus in the south, Greece was inundated with refugees and migrants after border shutdowns cascaded through the Balkans, stranding at least 20,000 in the country.

At Idomeni, a small community on the border with Macedonia, Reuters witnesses saw hundreds of families walking towards the frontier to join an estimated 3,000 more at a makeshift camp where many pitched tents in a field close to razor wire fence.

More than 500 km further south, hundreds of people were temporarily accommodated at a disused airport west of Athens. Sleeping mats were strewn across the terminal among biscuit wrappers as many women sat on the floor, some weeping.

“Planes bombed our homes, it was dangerous to stay there,” said mother of three Rajiya Zara, 38, nine months pregnant. “I’m afraid for my children.”

Between 300 and 400 people refused to stay at the airport, and took off on their own. “Help Us,” a large piece of paper held by one said. “We are human, open the borders”, read another, scrawled on a sleeping mat.

WE DIDN’T START IT

Athens on Thursday recalled its ambassador to Austria in anger over the border closures and has threatened to block European Union decision-making unless the bloc comes up with concerted action to deal with the crisis.

In the latest measure to slow the northward movement of migrants, the police chiefs of Slovenia, Austria, Macedonia, Serbia and Croatia agreed to limit the flow to about 580 per day per country, Slovenian police said on Friday.

The police chiefs are “obliged to limit daily transit through Western Balkans countries to a number which would enable a control of every migrant according to Schengen rules,” the police said.

Austria had earlier in the week hosted a summit of Balkan nations on how to regulate the migrant flows, but did not invite Athens. “Greece is being attacked by short-sighted countries, as if we were bombing Syria or created the refugee flows,” said Nikos Kotzias, Greece’s foreign minister.

Greece asked its passenger ferry companies and travel agencies on Friday to cut back on bringing migrants and refugees from frontline islands to the mainland and said its own chartered ships would stay put for a few days.

The moves, described by Greece’s shipping minister as temporary, are designed to stem a flow of people mostly fleeing violence in the Middle East.

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Most refugees arrive in the European Union after a short but at times dangerous journey by small boats from Turkey to nearby Greek islands such as Lesbos.

“We have taken some actions because of border closings, including an increase of temporary shelter spaces and a relative slowdown of the transport of migrants from the islands to the port of Piraeus,” Shipping Minister Thodoris Dritsas told Skai TV.

He said three ships chartered specifically to move migrants to the Greek mainland would be docked at the islands and accommodate refugees for “two or three days”.

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“It is a small scale slowdown (of flows to the mainland),” he said.

Macedonia, to the immediate north, is accepting only Iraqis and Syrians, witnesses say, with Afghans being turned back. Many of those who travelled the 550 km journey north only to be turned away sat in the stinking and overcrowded airport terminal on Friday, pondering their fate.

“I want to go to Germany,” said 18-year-old Nadershah Ahmedi, a student from Afghanistan. “When we came to Greece we heard the borders to Macedonia are closed for Afghans. Why can Syrians and Iraqis pass but not us?”