Danish Prime Minister Lars Loekke Rasmusssen told reporters in Copenhagen that as of noon Monday (1100 GMT, 6 a.m. EST), police were conducting spot checks on travelers crossing the border from Germany.
“We are introducing temporary border controls, but in a balanced way,” Loekke Rasmussen said, adding there would be no problem for “ordinary” Danes and Germans to cross the border.
It was the latest move by a European Union country to suspend an agreement to keep internal borders open after 1 million migrants entered the bloc in 2015.
“If the European Union cannot protect the external border you will see more and more countries forced to introduce temporary border controls,” the prime minister said.
He said the Danish move was in response to new ID checks introduced by Sweden on Monday for all passengers entering the country by train, bus or ferry.
To comply with the new Swedish rules, passengers had to show identification to board trains departing from Copenhagen Airport to Sweden across a bridge-and-tunnel link.
Danish officials have criticized the move and suggested Sweden should pay for the cost of the ID checks.
The Swedish government decided to tighten border controls after 160,000 people applied for asylum in Sweden last year — the highest number in Europe except for Germany. Most of them were from Syria, Iraq and Afghanistan.