European Commission President Jean-Claude Juncker has said that the European economy would suffer if its internal passport-free zone collapsed in the wake of Europe's worst migration crisis since WW2.
Speaking at a news conference in Brussels, Juncker said ending the Schengen agreement would make it harder for citizens of EU countries to find employment, and this would lead to less economic growth.
"Less Schengen means less employment, less economic growth," he said.
"Schengen is one of the biggest achievements of the European integration process."
The Schengen agreement, which is the EU's flagship policy of open borders, was drawn up in 1985. However, it's facing unprecedented pressure as migrants typically fleeing political upheaval in Africa and the Middle East stream into Europe.
Last year, more than one million arrived in the EU.
"Without Schengen, without the free movement of workers, without freedom of European citizens to travel, the euro makes no sense.. And the same applies to the link between Schengen, freedom of movement and the internal market," he said.
"If anybody wants to kill off Schengen, then ultimately what they are going to do is do away with the single market as well. And that's going to lead to unemployment issues in Europe."