The European Commission on Friday warned Denmark that it has "important doubts" about the legality of its plan to strengthen crime-fighting border controls as part of a domestic political deal, according to dpa. An initial legal assessment had raised "important doubts about whether the proposed measures, if implemented in the intensive and permanent way that has been announced, would be in line with Denmark's obligations under European and international law," commission spokeswoman Pia Ahrenkilde said. The European Union could launch infringement proceedings if the Danish border controls are put in place and are found to contravene the agreement governing the border-free Schengen zone and the bloc's internal market rules. Commission President Jose Manuel Barroso will spell out his concerns in a letter to Danish authorities, Ahrenkilde said. Barroso had already spoken by phone to Prime Minister Lars Lokke Rasmussen and "will take note" of the Danish government's assurances that its plan was within the law, she added. Barroso was encouraging Danish leaders to "refrain from unilateral steps and engage in dialogue" with the commission on the proposed steps' legality, she said. Denmark's minority government unveiled the border-control plan on Wednesday, a move it hopes will win concessions from right-wing populists in parliament on raising the early retirement age as part of its 2020 reform package. In addition to the deployment of more customs officials, scanners and other equipment to curb smuggling and detect suspicious vehicles would be used, Finance Minister Claus Hjort Frederiksen said. He expected the new measures to be in place in two or three weeks.