PARIS (Reuters) - The Italian government should keep cruise ships like the Costa Concordia away from its shores to protect some of the world's most beautiful heritage sites such as Venice and its Lagoon, the Paris-based United Nations cultural agency said on Monday.

UNESCO said it had sent a letter to Italy's Environment Minister Corrado Clini asking him to restrict the access of large cruise ships to culturally and ecologically important areas, following the capsizing of the Italian cruise liner on January 13 which left at least 15 dead.

"The tragic accident reinforces longstanding concern over the risk that large cruise liners pose to sites inscribed on UNESCO's World Heritage List," Assistant Director-General for Culture Francesco Bandarin wrote in the letter.

The Costa Concordia keeled over after hitting a rock near the Tuscan island of Giglio ten days ago, and is now lying on its side in shallow water as experts battle to pump some 2,400 tons of fuel from its hull before it spills into the sea.

Prosecutors have said the accident was caused by the captain steering too close to land, prompting calls from Italian environmentalists and politicians to ban big ships from sailing near the shoreline or in fragile areas.

UNESCO said some 300 cruiseliners visit Venice and its Lagoon each year, generating tides that erode the foundations of its buildings and contributing to the pollution of the area.

(Reporting By Vicky Buffery)