The mayor of Venice has urged Unesco to place the city on its world heritage site blacklist as he lambasted Italy’s transport minister for failing to endorse a plan to divert cruise ships from the busy Giudecca canal.

Luigi Brugnaro’s frustration has been brewing since a huge vessel crashed into a tourist boat on the canal in early June, injuring four people.

“We will write to Unesco to ask for the city to be put on the blacklist,” he told Radio 24. “Venice is in danger and we feel in danger.”

Brugnaro said the city had no faith in the government, and felt particularly let down by the transport minister, Danilo Toninelli, who has rejected a plan agreed by Italy’s previous administration that would have closed off the canal to cruise ships.

Facebook Twitter Pinterest The cruise ship MSC Opera is seen after the collision with a tourist boat. Photograph: Andrea Merola/EPA

After the crash, which provoked more protests against cruise ships in the lagoon, Toninelli said a solution would be announced soon. Toninelli, a member of the Five Star Movement, which often fights against major infrastructure projects, visited the city last week – by helicopter.

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A source at the local authority said he did not meet the city’s leaders to discuss the original plan or his alternative proposals, which include building a new cruise ship terminal at either the Lido San Nicolò or in Chioggia, a coastal town south of Venice. Toninelli has suggested putting the options to a referendum on his party’s online platform, Rousseau, which it often uses to craft policy.

“He has an arrogance that I have not seen in my life,” Brugnaro said. “We do not so much contest that the minister has a different idea to ours, and if he told us that would be nice, but in the meantime he is making [other] proposals to move the ships from St Mark’s Square.”

Facebook Twitter Pinterest A demonstration against cruise ships being allowed in the Lagoon of Venice. Photograph: Andrea Merola/EPA

Unesco originally gave authorities until 2017 to undertake measures to protect Venice’s monuments and preserve its fragile environment, or risk the city being put on its endangered world heritage list. That deadline was extended by a year, and again until 2021 as leaders showed encouraging signs of making improvements in terms of managing the tourism flow.

Their most crucial task, however, was to come up with a plan to divert cruise ships. The project agreed in 2017 foresaw those weighing more than 96,000 tonnes entering the lagoon via the Malamocco canal to reach the mainland area of Marghera, where a passenger terminal would be built. Medium-sized vessels would go past Marghera and take the longer route through the Vittorio Emanuele canal before reaching the Marittima terminal, where cruise liners currently dock.