Speaking from a checkpoint on the border with France near the city of Saarbrücken, DW's Lucia Schulten explained how some of the controls appeared.

"Cars slow down and when the police officers decide to check one car they pull over here to the side and they have to drive in front of the police station where their papers are checked," she said.

"Since we've been standing here we've seen one of these long-distance buses being checked. Police went in there and checked the papers of everyone sitting in  there and they also took one man out who had to go into the police station."

Schulten explained that German Chancellor Olaf Scholz had been speaking to other European leaders over the weekend, with some expressing their concern about the checks.

"A lot will probably depend on what these checks will look like and what they will mean for the free movement of persons and goods within the European Union and if this will be a hindrance to them or not."