A risky practice by cruise ships of close-passing the island of Giglio in a foghorn-blasting salute to the local population appears to have contributed to the Costa Concordia disaster, officials and witnesses said on Sunday.
The 114,500 tonne monster cruise liner sank after hitting a reef only 300 metres (985 feet) from shore late Friday as it passed much too close to the shore of the Tuscan island on its route to Savona in northern Italy.
Defence Minister Giampaolo Di Paola, a former Italian navy admiral, blamed "gross human error" for the disaster in comments to Rai3 television on Sunday.
"Ships of such dimensions cannot sail so close to a coastline where one knows there are rocks," the minister said.
Some witnesses said the ship was indulging the local population with a spectacular parade past the island in what is known locally as an "inchino" or reverent bow, with its upper decks ablaze with light as many of the passengers sat down to dinner.
Adding weight to the theory, the daily La Stampa on Sunday published a letter dated last August in which Giglio's mayor Sergio Ortelli thanked the Concordia's captain for the "incredible spectacle" of a previous close pass.
The mayor told journalists on the island on Saturday that the normal route for cruise ships heading north from the port of Civitavecchia near Rome takes them to within three to five kilometres (1.8 to 3.1 miles) of Giglio. "Many of them pass close to Giglio to salute the local population with blasts from their sirens."
"It's a very nice show to see, the ship all lit up when you see it from the land. This time round it went wrong," said the mayor.
On Sunday however, Ortelli denied that it was a regular practice to come so close to the island.
"It's not the practice, or in any way a programmed salute but always in safe conditions," he said.
Ortelli said some skippers of Costa cruise liners liked to "pay tribute" to former colleagues who have retired to the island but that this always occurred in "safe conditions".
Francesco Verusio, the Tuscany region's chief prosecutor, said the ship's captain "should not have been sailing so close to the island" and had him arrested for multiple homicide and abandoning his ship before all the passengers were off.
He said that the captain had "approached Giglio in a very awkward manner", which led the ship to "hit a rock that became embedded in its left side, causing it to list and take in an enormous amount of water in the space of two or three minutes".
Enrico Rossi, the president of the Tuscany region, visited the island on Sunday to see the rescue effort at first hand. He said he would ask the environment ministry on Monday to ensure that cruise ships adhere strictly to navigation rules in future.
"It's shocking to learn that a ship of this size can navigate so close to the coast," Rossi told AFP, adding that it should be possible to balance the need to entertain passengers with the safety of the ship.