In an interview with Germany's "Bild" newspaper on Tuesday, Steinmeier spoke of the "danger" if Europeans lost their right to freedom of movement and travel after two countries reviewed their commitment to Europe's Schengen borderless travel zone.

On Monday, Denmark said it would begin random passport checks at its border with Germany. Sweden has also imposed new security checks on those traveling from Denmark by train, ferry and bus.

Adding his voice to widespread criticism of the move in Berlin, Steinmeier said he was convinced the right to freedom of movement and freedom to travel was "perhaps Europe's greatest achievement." When asked whether the future of Schengen zone was in danger, he replied, "I hope not but I can see the risk."

He renewed his called for EU countries to "join forces to find European solutions to the refugee flow, while at the same time protecting our European external borders effectively."

Berlin urges dialogue

Erwin Sellering, the premier of Germany's northern Mecklenburg-Western Pomerania state, also expressed his concern about Denmark's reintroduction of passport controls at the German border, calling for an EU-wide response.

He told radio broadcaster NDR Info that he did not expect to see a backlog of refugees gathering in northern Germany, waiting to enter Denmark.

In defense of the new controls, which took effect on Monday, Danish Prime Minister Lars Lokke Rasmussen said the "temporary measure" would help to deal with an influx of refugees arriving in the country and prevent migrants without papers from entering.

Germany's public railway firm responded that it would not check passports on the country's border with Denmark, leaving that task up to the Danish police.

"Our personnel do not have the necessary knowledge," to conduct such checks, said a spokesman from Deutsche Bahn.

Denmark and Sweden both joined the Schengen zone in 2001, which allows much of the EU and a handful of other European countries to operate as single country for international travel purposes, with the removal of internal borders and a common visa policy.

Denmark received 21,000 asylum requests in 2015, while its two neighbors bore the brunt of the crisis, with Germany reporting around 1.1 million applicants and Sweden 163,000.

mm/se (AFP, dpa)