More time and money will be needed to remove the Costa Concordia from the rocks off Tuscany where it capsized last year, in part to ensure the toxic materials still trapped inside don't leak into the marine sanctuary when it is righted, officials said Saturday.

On the eve of the first anniversary of the grounding, environmental and salvage experts gave an update on the unprecedented removal project underway, stressing the massive size of the ship — 102,000 tonnes, its precarious perch on the rocks off Giglio island's port and the environmental concerns at play.

The pristine waters surrounding Giglio are part of a protected marine sanctuary for dolphins, porpoises and whales, and are a favourite for scuba divers. Already, tourism was off 28 per cent last year thanks in part to the eyesore in Giglio's port, and officials say the hulking vessel now won't be removed before the end of this summer.

Franco Gabriele, the head of Italy's civil protection agency, told reporters that officials were now looking at September as the probable date for removal, taking into account conservative estimates for poor weather and rough seas. Originally, officials had said they hoped to have it removed in early 2013.

In addition, Gabriele and Costa officials said the cost might now reach about $530 million, up from the $400 million originally estimated.

Captain's stunt kills 32

The Concordia slammed into a reef off Giglio on Jan. 13, 2012, after the captain took it off course in a stunt to bring it closer to the island. As it took on water through the 70-metre gash in its hull, the Concordia rolled onto its side and came to rest on the rocks off Giglio's port. Thirty-two people were killed.

'During the rollover and floating operations, there could be some leaking.' —Maria Sargentini, head of environmental oversight group

The captain, Francesco Schettino, remains under house arrest, accused of multiple manslaughter, causing a shipwreck and leaving the ship before all passengers were evacuated. He hasn't been charged. Schettino maintains he saved lives by bringing the ship closer to shore and claims the reef wasn't on his nautical charts.

Salvage crews successfully removed some 1,900 tonnes of fuel last year from the ship's tanks without any major spill. But Maria Sargentini, president of the environmental oversight group for the Concordia, said sewage, remaining fuel and tons of rotten food remain inside.

"Sure, there are still some risks," she said Saturday. "Especially during the rollover and floating operations, there could be some leaking."

The complicated removal plan involves constructing an underwater platform and attaching empty tanks on the exposed side of the ship. The cisterns will be filled with water, and cranes attached to the platform will be used to rotate the ship and pull it upright.

Once upright, the ship will have cisterns attached to the other side. All the cisterns will be emptied of water and filled with air to help float the ship and free itself from the seabed. Once it's properly afloat, it can then be towed to a nearby seaport for demolition.

On Sunday, relatives of the dead and some survivors are expected to flock to Giglio for a daylong commemoration that will honour the victims, those who rescued them and the residents of Giglio who opened their doors to the survivors.