European Union nations have agreed to allow countries to temporarily restore border checks in the visa-free area if needed to curb illegal immigration.

Interior ministers of nations in the so-called Schengen zone agreed on the new rule Thursday in Luxembourg. The visa-free zone includes most of the EU countries, and also Iceland, Norway, Switzerland and Liechtenstein. It operates like a single state with border controls for those travelling in and out of the area, but with no internal border controls. Once an illegal migrant enters the Schengen zone, he or she can move freely from one country to another.

Currently, the Schengen treaty allows renewal of border controls in case of terror or security threats.

Under the new rule a member nation can reintroduce border controls temporarily if it determines that a surge of immigration could pose a serious threat to public order or domestic security.

European Parliament in Brussels has opposed the idea saying it undermines European unity. EU Home Affairs Commissioner Cecilia Malmstroem said negotiations on the issue would continue.

Germany and France, Europe's two biggest economies, have long insisted that the decision must be left to national governments.

Anti-immigration debates increased over the past year, especially after the popular uprisings in the Arab world spurred thousands form the Middle East and North Africa to flee to Europe.

Greece's economic crisis and growing unemployment are raising concerns that many Greeks would move west in search of a living.