Large cruise ships will be banned from sailing into the centre of Venice from 1 August amid fears they are causing irreparable damage to the lagoon city, Italy's government has said.

"The decree adopted today represents an important step for the protection of the Venetian lagoon system," Prime Minister Mario Draghi said in a statement.

Instead, they will be diverted to the city's industrial port of Marghera, although this is viewed as only a temporary solution, with ministers calling for ideas on a new permanent terminal.

Campaigners have for years been calling for cruise ships to be banned from sailing past the iconic St Mark's Square, saying they cause large waves that undermine the city's foundations and harm the fragile ecosystem of its lagoon.

The debate was reignited by the return last month of cruise ships after months of quiet in the city during the coronavirus pandemic.

Late last month the UN's cultural agency, UNESCO, recommended Venice be put on a list of "World Heritage in Danger" sites ahead of a meeting of its World Heritage Committee in China starting Friday.

Infrastructure minister Enrico Giovannini said the ban was a "necessary step to protect the environmental, landscape, artistic and cultural integrity of Venice".

The ban will apply to ships which fulfil any of four criteria: weighing more than 25,000 tonnes, measuring more than 180 metres long, more than 35 metres high or producing more than 0.1% sulphur.

Ships that do not fulfil one of these criteria - notably smaller cruise ships with around 200 passengers - are considered "sustainable" and will continue to be able to dock in Venice centre.

The vice-president of tourism association Confturismo, Marco Michielli, said the new law represented a "good compromise".

"The Marghera solution would maintain port activity in Venice, on the one hand safeguard jobs and activities, and on the other free up the Giudecca Canal on the other," he said.

The issue of cruise ships in Venice has sparked global debate, and last month celebrities and cultural figures including Mick Jagger, Francis Ford Coppola and Richard Armstrong, director of the New York's Solomon R Guggenheim Museum, issued a call for action.

In an open letter to the Italian government calling for a range of measures to better protect the city, they warned the historic site risked being "swept away" by cruise ships.