Austria has announced it is going to build a fence along its border with Slovenia to slow down the flow of refugees trying to enter the country.
Both countries are part of the passport-free Schengen zone.
The Austrian Interior Minister said the move was designed to ensure an orderly, controlled entry into the country.
It is reported refugees are becoming more and more emotional and aggressive as they have to wait for hours in freezing temperatures.
But Austria's government insists it is not shutting down the border with its EU neighbour.
The project is likely to lead to criticism for the signal it sends to other nations struggling to cope with the migrant influx, and because of associations with the razor-wire fence Hungary has built to keep migrants out - a move Austria strongly criticised.
Since the Hungarians sealed their borders a few weeks ago, thousands of migrants using the western Balkans route into Austria and beyond have been flowing into Croatia and then Slovenia on a daily basis.
Slovenian officials suggested even before Austria’s announcement that they too are considering a fence, in their case on the border with Croatia.
Slovenian prime minister Miro Cerar said on Wednesday that “if necessary, we are ready to put up the fence immediately”, in case a plan by EU and Balkan leaders fails to stem the migrant surge.