ATHENS: Greek police started removing migrants from the Greek-Macedonian border on Tuesday after additional passage restrictions imposed by Macedonian authorities left hundreds of them stranded, sources said.

The migrants had squatted on rail lines in the Idomeni area on Monday after attempting to push through the border to Macedonia, angry at delays and additional restrictions in crossing.

Greek police and empty buses had entered the area before dawn, a Reuters witness said. In one area seen from the Macedonian side of the border, about 600 people had been surrounded by Greek police, the witness said.

There were an estimated 1,200 people at Idomeni, in their vast majority Afghans or individuals without proper travel documents. A crush developed there on Monday after Macedonian authorities demanded additional travel documentation, including passports, for people crossing into the territory.

Some countries used by migrants as a corridor into wealthier northern Europe are imposing restrictions on passage, prompting those further down the chain to impose similar restrictions for fear of a bottleneck in their own country.

But there are concerns at what may happen in Greece, where a influx continues unabated to its islands daily from Turkey. On Tuesday morning, a further 1,250 migrants arrived in Athens by ferry from three Greek islands.

Some of them had bus tickets to Idomeni, but it was unclear if they would be permitted to travel north from Athens.