EU ministers paved the way Monday for national border controls to be in effect longer than the six months currently allowed, arguing that efforts to control the continent's migration surge are having little effect.
More than 1 million migrants and refugees reached Europe last year, straining local resources and creating tensions between European countries.
EU interior ministers met in Amsterdam on Monday to discuss their response to the refugee crisis, most notably when it comes to border controls.
The Schengen free-travel zone allows people to move around freely through 26 European countries, normally without the need for passports or border checks.
But Germany, Austria, Sweden, Denmark and Norway have reintroduced temporary border controls to better manage the migration surge into their countries. Under current provisions, they can only do so for a period of six months.
"The unprecedented influx of asylum seekers, which compelled member states to take these measures nationally, have not decreased yet," Dutch Migration Minister Klaas Dijkhoff said following Monday's talks.
The ministers asked the European Commission to prepare the "legal and practical basis" for border controls to continue, Dijkhoff added. He chaired the migration talks, as the Netherlands currently holds the European Union's rotating presidency.
EU Migration Commissioner Dimitris Avramopoulos recognized that some countries might have to extend controls if "serious risks for public order and internal security" remain, adding that the European Union's executive was looking at the available options.
Currently, most migrants travel from Turkey to Greece and on through the Balkans to reach northern European nations.
Athens has come under particular fire for letting people move through its territory largely unchecked, even though it is supposed to police its border with Turkey, one of Schengen's external frontiers.
Some member states have gone so far as to suggest that Greece could be excluded from Schengen.
"If people do not manage to secure the European external borders - that is the Turkish-Greek border - then the external Schengen border will move back towards Central Europe," Austrian Interior Minister Johanna Mikl-Leitner threatened Monday, ahead of the Amsterdam talks.
"It is a myth to think that the Greek-Turkish border cannot be secured. The Greek navy has sufficient capacities to protect this border," she added.
German Interior Minister Thomas de Maiziere told journalists that pressure would be put on Athens so that "Greece does its homework."
"We need to look very closely at the position of Greece within Schengen," Belgian Interior Minister Jan Jambon added. "First and foremost, Greece has to do what it has to do - namely controls."
But the commission rejected the suggestion that Greece could be forced out of the 26-country Schengen area.
"There is no plan to exclude Greece from anything. We never discussed either a suspension of Schengen or the exclusion of a Schengen member," said Natasha Bertaud, a spokeswoman for the European Union's executive.
The move to extend national border controls is not aimed at "pushing a country out," Dijkhoff stressed following the talks.
Greek Deputy Immigration Minister Ioannis Mouzalas complained about the "blame game" against Athens, arguing that the country is becoming "better and better" at identifying migrants upon arrival.
Meanwhile, several EU ministers warned about the risk of chipping away at the unity of the Schengen bloc.
"In no case should we abandon Schengen, it is really the be-all and end-all of the EU," said Luxembourg Deputy Prime Minister Etienne Schneider.
"Europe must remain a stable structure ... There cannot be bits of Europe inside and bits of Europe outside because that would be the start of dissolution," Italian Interior Minister Angelino Alfano added.
But there is already speculation that Schengen's free-travel principle is at risk of crumbling due to the resumption of national border checks.
"Schengen and freedom of movement is one of the biggest achievements of European integration. We have to do all that is possible to safeguard it," Avramopoulos said in an interview with the Italian daily Il Messagero published Monday.
"The refugee crisis today is threatening something bigger than simply the Schengen treaty," he added. "European unity as a whole is at stake."