BERLIN - German Foreign Minister Frank-Walter Steinmeier warned on Tuesday that European freedom of movement could be at risk after two countries reviewed their commitment to the Schengen borderless travel zone.

Denmark said on Monday that it would reintroduce passport checks at its border with Germany in a bid to deter refugees without identification papers.

Sweden has also imposed new security checks on those traveling from Denmark by train, ferry, and bus.

In an interview with German Bild newspaper on Tuesday, Steinmeier said he was convinced that the right to freedom of movement and travel was "perhaps Europe's greatest achievement."

When asked whether freedom of travel in the Schengen zone is in danger, he replied, "I hope not, but I can see the risk."

The minister renewed his call 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." (Xinhua)