Michele Vianello, the deputy mayor, said the tax would be about 40p per visitor and levied on hotel, restaurant and other bills.

"It will be a consumers' tax. The only question is whether it can be made legal. The taxes for Venetians will not be increased."

The project, which is being considered by Venice's Centre-Left council, comes after different charges for tourists and Venetians were introduced for basic services. Visitors must now pay twice as much to use public lavatories.

Venice attracts 12 million tourists each year, so it could earn £5 million a year from the tax. The city spends more than £7 million annually on clearing rubbish, much generated by visitors.

Mr Vianello said in an interview yesterday: "I would like to remind people that Venice is a city that has to serve 12 million people, while the brunt of these services is being met by only 300,000: the [mainland and island] residents."

Ugo Samueli, president of the local hoteliers' association, agreed with the tax in principle but disagreed with the proposed ways of collecting it.

Elio Dazzo, a local official, believed the tax should be levied on the tour operators.