The 17-deck cruise ship that capsized smack in the middle of a marine nature reserve off Tuscany shows these ocean giants threaten the coastline and should be banned, Italian environmentalists said Monday.

The Costa Concordia remains on its side less than 50 metres (55 yards) from the island of Giglio with more than 2,000 tonnes of diesel oil and slowly releasing objects ranging from refrigerators to cabin furniture and carpeting.

Worried about the impact on the environment, some are calling for banning these colossal ships -- as big as a 10-storey buildings -- from sailing into these sensitive zones.

"That's enough, we have to stop treating these ships like they were simple vaporetti," said Italy's Environment Minister Corrado Clini, referring to the boats that ply the canals of Venice.

He promised to act "to prevent these giant ships from getting close to sensitive zones" to protect the environment in an interview published Monday in La Stampa newspaper.

Three senators from the leftist Democrat Party also demanded that the government issue an emergency decree to ban cruise ships and oil tankers from passing near sensitive areas, including the lagoon of Venice, protected marine zones and the waters around small islands.

Italian environmental group Marevivo slammed the "proven and widespread" practice of allowing cruise liners close to shore "to create a picturesque setting both on board and on land."

It joined the chorus calling for a ban on sailing near fragile zones, like the Tuscan archipelago.

The Tuscan islands of Elba, Giglio, Capraia, Montecristo, Pianosa, Giannutri and Gorgona have formed since 1996 one of the biggest marine parks in Europe.

Protests against cruise ships were planned for this month in Venice even before last weekend's accident on the other side of the peninsula that left at least six people dead.

Activists have been working to ban the huge vessels from mooring off Saint Mark's basin in Venice, a regular stop on cruises that bring 1.6 million passengers to the region each year.

Mario Tozzi, a geologist and ex-president of the protected reserve, said the Costa Concordia strayed from its route of about five kilometres (3.1 miles) offshore "to perhaps see the lights of Giglio close up as well as the landscape and see how it ended.

"Tourism should not involve recklessness," he added.

The cause of the accident late Friday has so far been alleged as human error with Italian media reporting that the captain wanted to sail near Giglio to please the head waiter who hails from there.

The head of the company which owns the monster vessel said it ran aground as a result of an "inexplicable" error by the captain, Francesco Schettino, who was arrested Saturday along with first officer Ciro Ambrosio.

"He carried out a manoeuvre which had not been approved by us and we disassociate ourselves from such behaviour," said Pier Luigi Foschi, the boss of Costa Crociere, Europe's largest cruise operator.

For Tozzi there is no question that super-tankers and cruise ships should be banned from this Mediterranean sanctuary for marine mammals, an area that forms a triangle from the French Riviera to Corsica to the Tuscan coastline.

Last year, about 5.4 million Europeans took cruise holidays, more than double the 2.6 million recorded in 2006, according to the European Cruise Council.