Extra border control will be put in place by German authorities during Hamburg's hosting of the G20 summit from July 7th, reports DR.
This is likely to result in extensive queueing on Denmark's southbound E45 motorway, Mette Nedergaard of the Danish Road Directorate's (Vejdirektoratet) traffic department told the broadcaster.
“We saw last year that significant queues arose when motorists were returning from Germany to Denmark. This year, we can also expect queues when Danes drive to Germany,” she said.
Estimated waiting times to cross the border are around 30 minutes, Nedergaard said.
The temporary German border control will remain in place until July 11th.
Denmark's own border controls with Germany, which were introduced in January 2016 and have seen border police return to the Schleswig-Holstein frontier, have remained in place through repeated extensions for three six-month periods.
Denmark introduced border control as a result of a peak in the flow of migrants in 2015.
Last month, the EU approved the extension of border controls in Denmark, Sweden, Germany, Austria and Norway, with the proviso that they will likely be lifted in October. This means that any further extension would require a different justification to be put forward by the Danish government.
EU rules which allow Schengen zone countries to reinstate border checks under exceptional circumstances.