Germany is prolonging controls along the country’s border with Austria by six months due to a high number of illegal entries, AP said, citing officials. The checks were meant to expire on November 11.

The border between Austria and southern Germany was the main crossing point for hundreds of thousands of migrants who sought refuge in Europe in 2015 and 2016.

Both countries are part of Europe’s Schengen travel area that allows passport-free travel across much of the continent. Countries are allowed to reintroduce border controls only under exceptional circumstances.

Interior Ministry spokesman Steve Alter said on Wednesday that German border police recorded 6,749 illegal entries from Austria between January and the end of August, and turned back 3,792 people during that period.