Refugees at the Greek-Macedonian border on Tuesday were forcefully removed by Greek police after Macedonia imposed restrictions on its border and left hundreds stranded for not having passports, sources said.
The migrants had squatted on rail lines in the Idomeni area on Monday after attempting to cross the border to Macedonia, despairing at delays and additional restrictions.
Greek police and empty buses entered the area before dawn, a Reuters witness said. Some 600 people were surrounded by Greek police in one area seen from the Macedonian side of the border, the witness said.
Police said 2,000 people were stranded at Idomeni when Macedonian authorities demanded additional travel documentation, including passports for people crossing into the territory.
The European Union is failing to deal with unilateral actions from individual member states, Ionnis Mouzalas, a Greek deputy minister for migration said.
Macedonia, Austria, Hungary, Slovenia, Serbia and Croatia have all started tightening their borders under new regulations, prompting those further down the chain to impose similar restrictions for fear of a bottleneck in their own country.
There are concerns over what may happen in Greece, where an influx continues to its Islands from Turkey, while Turkey hosts the most refugees in the world, having opened its doors 2.5 million people fleeing the Syrian civil war.
More than a million refugees reached Europe in 2015, most of them transiting through Greece.
On Tuesday morning 1,250 migrants arrived in Athens by ferry from three Greek Islands.
Some had bus tickets to Idomeni, but it is not clear if they would be permitted to travel north from Athens.