Italy on Tuesday banned cruise liners from Venice lagoon to defend its ecosystem and heritage, moving to end years of hesitation and putting the demands of residents and culture bodies above those of the tourist industry.

The government decided to act after the UN culture organisation Unesco threatened to put Italy on a blacklist for not banning liners from the World Heritage site, cabinet sources said.

The ban will take effect from August 1, barring ships weighing more than 25,000 tonnes from the shallow Giudecca Canal that leads past Piazza San Marco, the city’s most famous landmark.

“I am proud of a commitment that had been honoured,” culture minister Dario Franceschini said in a tweet announcing the cabinet’s approval of the decree, confirming a previous Reuters report.

The legislation, which is likely to affect the business of cruise companies such as Carnival Cruises, provides compensation for firms and workers involved, a culture ministry statement said.

Carnival cruises was not immediately available to comment.

Venice residents and the international community have been urging governments for years to ban large ships passing through the lagoon, polluting and threatening the stability of its buildings and fragile ecosystem.

Such concerns clash with the interests of port authorities and tourist operators who say the city needs the business offered by the cruise industry.

The 25,000-ton threshold will mean only small passenger ferries and goods vessels can use the Giudecca, excluding all cruise liners which typically weigh at least four times as much and can reach more than 200,000 tons.

Francesco Galietti, Italian director of the international cruise industry trade association CLIA, said the group welcomed an alternative route for cruise ships and he called the latest government move “a major step forward”. Rome has passed legislation numerous times in the past to limit liners’ access to one of the world’s most famous tourist sites, but an alternative docking point is not yet ready.