EU interior ministers meeting in Amsterdam are seeking to beef up controls at the EU’s external borders, to stem the flow of migrants heading north from Greece and Macedonia.
Under the EU’s current Schengen rules, Germany’s temporary border controls are set to end in May.
But reports say Germany and some other countries want to extend those controls – possibly until the end of 2017.
The migrant crisis has put the Schengen passport-free travel zone at risk.
Austria’s Interior Minister Johanna Mikl-Leitner warned Greece that it could be excluded from the Schengen zone if it failed to put more resources into curbing the migrant influx.
Interviewed by Germany’s Welt am Sonntag newspaper, she said that “if the Athens government doesn’t, in the end, do more to protect the [EU] external borders, then we’ll have to openly discuss a temporary exclusion of Greece from the Schengen zone”.
German Foreign Minister Frank-Walter Steinmeier criticised her threat, saying such “pretend solutions” would “not help anyone to move forward” in the migrant crisis.
Germany is the main destination of the irregular migrants – an estimated 1.1 million entered the country last year, most of them refugees from the conflicts in Syria, Iraq and Afghanistan.
More than 30,000 migrants have already reached Greece from Turkey by boat this year, despite the cold weather and rough seas.
Greece – with many islands lying near the Turkish coast – is the main entry point, and is overwhelmed by the numbers.
Some 108,000 migrants arrived in Greece in December, the EU border agency Frontex said.
Besides Germany, five other Schengen states have put temporary border controls in place: Austria, Denmark, France, Norway (not an EU member) and Sweden.
Schengen – seen as a cornerstone of EU freedom – embraces 22 EU members and four non-EU countries.
Macedonia – not in Schengen – is only letting through migrants whose Greek registration papers show their final destination to be Germany or Austria.
Slovenia – one of the countries on the Balkan migration route – has urged its EU partners to provide “maximum assistance to the Macedonian authorities” by sending border police and equipment to deal with the crisis.