“I expect the European Commission as guardian of (EU) treaties to probe the compatibility of the Danish decision with European law,” she told the daily Hamburger Abendblatt in comments to be published on Saturday.
Leutheusser-Schnarrenberger said Copenhagen's move to reimpose customs checks on border crossings with Germany and Sweden was a “bad day for Europe” and in clear violation of its EU treaty obligations.
Denmark's minority government, prodded by the far-right populist DVP party, on Friday announced it would start to make random checks starting next week ostensibly to stem the flow of criminals from eastern Europe. But the EU and the country's neighbours have argued they will impinge on the freedom of movement within the visa-free Schengen area.
Danish officials on Friday tried to play down the impact of the border checks, saying they would not hinder traffic and trade.
“The vast majority of travellers won't notice the checks. We welcome German holidaymakers,” said Peter Christensen, the Danish minister responsible for customs and taxation.
Starting on Tuesday, 30 customs agents on the German border and 20 officers at Swedish crossings will make stops to search for drugs, weapons and illegal sums of money. Next year the number of agents will increase and Denmark will install electronic scanning equipment and build new customs houses along major road and rail routes.