Sweden began checking documents of travelers from Denmark on Monday for the first time in half a century, causing delays of trains and frustration among travelers, Al Jazeera wrote.
Those without valid ID documents are denied to board buses, trains and ferries bound for Sweden, but cars are exempt from checks.
Denmark's prime minister said Sweden's move gave his country no option but to impose its own border controls. He appealed to the European Union to take "collective decisions" to better protect its external borders against the tide of migrants and refugees.
"The Swedish ID checks can increase the risk of a large number of illegal immigrants to accumulate in and around Copenhagen," Lars Lokke Rasmussen said in Copenhagen, justifying the new controls on the German border.
Last year about 163,000 refugees sought asylum in Sweden, the largest number for any EU country relative to its population.
But with arrivals running at around 10,000 a week in November, mostly travelling through Denmark, the Swedish government has said it is time to tighten border controls and asylum rules.
