Venice will trial a long-debated ticketing system from spring next year, officials said Tuesday, with day-trippers charged five euros to enter the Italian city's historic center in an attempt to cut tourist numbers.

The council executive backed the move just weeks after U.N. cultural agency UNESCO recommended Venice be added to its list of world heritage sites in danger, in part because of the impact of mass tourism.

"Regulating tourist flows in certain periods is necessary, but that does not mean closing the city," said mayor Luigi Brugnaro.