Switzerland and Italy are in a diplomatic dispute over Switzerland’s decision to close three secondary border crossings at night in a bid to fight crime.

Italy’s Foreign Ministry on Tuesday summoned the Swiss ambassador for urgent talks, emphasizing that the closings violate Europe’s norms on free circulation.

In an email, the press office of the Swiss Department of Foreign Affairs said Ambassador Giancarlo Kessler “took note” of the message from Italian authorities and pledged to keep them informed on the results from what it characterized as an experiment.

Italian mayors in the affected region had protested the closures as penalizing Italians who legitimately cross the border for work or other reasons.

The crossings from the Italian provinces of Como and Varese have an average nightly traffic of 90 vehicles during the week and 110 vehicles on weekends, 20 percent of which are Swiss vehicles, according to Swiss authorities.

Switzerland started closing the three border crossings at night on April 1 as part of a six-month pilot program. The move, approved by the Swiss parliament, follows a brief surge of migration into the Italian-speaking Swiss region of Ticino last summer from Italy, which has seen the arrival of tens of thousands of migrants rescued at sea.

The populist Swiss People’s Party, which has the most seats in parliament, has led the push to restrict access both to citizens of European Union countries who want to work in Switzerland and to migrants who have arrived in Europe from Africa and the Middle East.

Switzerland is not a member of the European Union, but adheres to the “Schengen zone” rules that allow for unimpeded cross-border travel and trade on the continent.

Kessler said Switzerland “had informed the Italian authorities on several occasions” about the project, including during a meeting of their two countries’ foreign ministers last month, according to the foreign affairs department.