MACEDONIA (REUTERS) - At the Greek border crossing in Idomeni, the wait to move north into Macedonia seems interminable.

Macedonia's been opening its border only in short intervals this week to stifle the flow of migrants. Only a few hundred refugees can pass each day, so about 3,500 of them have become trapped here, their numbers swelling.

"I cannot imagine 10,000 people coming here today or tomorrow, this will be a big problem." said Azis, a Syrian migrant from Aleppo.

The wait feels so long, they have bunkered down in a "tent city"', frustrated by reports that authorities plan to further restrict the flow, limiting access to Afghan migrants.

German writer Philip Breu has been witness to the scenes.

"There is always this fear that the border might be shut down or there is maybe, that they maybe wait for too long and the border is suddenly stopped for days or maybe forever, no one knows, you know. A rumor spreads and people panic suddenly, very quickly." said Breu.

Austria and Balkan states are discussing a coordinated strategy to deal with Europe's migrant flow, but meanwhile in Idomeni, the families can only wait and deal the best they can with the winter chill.