GIGLIO, Italy -- More time and money will be needed to remove the Costa Concordia cruise ship 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.

As shipwreck survivors and relatives of the 32 killed began arriving on the island of Giglio to mark Sunday's anniversary of the grounding, environmental and salvage experts gave an update on the unprecedented removal project under way.

They stressed the massive size of the ship -- 112,000 tons -- its precarious perch on the rocks off Giglio's port and the environmental concerns at play in explaining the delays and problems in rolling the ship off its side and towing it intact from its resting place.

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.

Franco Gabrielli, the head of Italy's civil protection agency, told reporters that officials are now looking at September as the probable date to remove the ship, taking into account conservative estimates for poor weather and rough seas. Originally, officials had said they hoped to tow it from Giglio's waters by early 2013.

In addition, Gabriele and Costa officials said the cost might now reach (euro)400 million ($530 million), up from the (euro)300 million ($400 million) originally estimated.

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-meter (230-foot) 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.

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.

Relatives of the dead and survivors began flocking to Giglio on Saturday ahead of Sunday's daylong commemoration to honour the 32 victims, those who rescued them and the residents of Giglio who opened their doors to the 4,200 passengers and crew who survived.

"Just seeing this boat has a powerful effect on me," said Albert Karianis, a 60-year-old cleaner from Marseille, France, who survived the shipwreck and returned Saturday to the island for the first time.

"I think about it every day, and I have nightmares," he said.

Hilaire Blemand, the father of victim Michael Blemand, said he came back to honour his son and take part in the commemoration Mass for the victims.

"You always have a feeling of apprehension when you return to where it all started, and when you see that the ship is still there, it is still just as painful," he said.

Also arriving on Giglio on Saturday was Capt. Gregorio De Falco of the Italian coast guard in Livorno, who became something of a hero to survivors after his recorded conversations with Schettino during the evacuation were made public. In the conversations, De Falco excoriates Schettino for having abandoned the ship before all passengers were off and orders him to return, shouting the now-infamous order "Go on board (expletive)!"

De Falco told RAI state television he wanted to go to Giglio to "embrace the victims, and the relatives of the victims." De Falco, who has shied from all media attention since the disaster, said he did so because he didn't want the "notoriety."

"I don't want notoriety for this tragedy. I have always avoided it."

While groups of survivors were arriving on the island -- some on specially organized ferries -- others received a letter from Costa urging them to stay away, saying there wasn't room for them and that the commemoration was for families of those who died. Those who received the letter speculated that Costa simply didn't want disgruntled passengers speaking to the media.

Nevertheless, some such passengers were on hand.

Violet Morra, a 65-year-old from Marseille, said she had rejected Costa's initial settlement offer of (euro)11,000 euros per passenger, offered in the immediate aftermath of the grounding. Many survivors rejected the offer and are pursuing legal action against the company and its Miami-based parent company Carnival Corp., the world's largest cruise line.

Passengers recounted a harrowing and chaotic evacuation, with crew members giving contradictory instructions and the captain delaying the evacuation order for a full hour after impact. By the time he gave the order, the ship was at such a tilt that many lifeboats couldn't be lowered.

"It meant that our lives were only worth (euro)11,000, just (euro)11,000 euro for our lives," Morra said. "We are still facing psychological problems, and so we have rejected it."

Costa attorney Marco De Luca said the compensation procedures are going ahead "at a satisfactory pace." He said almost two-thirds of the passengers took Costa's compensation offer.

Costa is fighting legal efforts, particularly those in the United States, where damage awards are likely to be higher than in Italy. Costa is challenging the jurisdiction of U.S. courts to hear the cases, arguing among other things that in buying their cruise tickets, passengers entered into a contract with Costa that selects the courts of Genoa, Italy, as the exclusive forum for any claims against the company.

The plan to roll the Costa off its side and remove it from its resting place involves constructing an underwater platform and attaching empty cisterns 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 it from the seabed. Once it's properly afloat, it can then be towed to a nearby seaport for demolition.

Salvage crews successfully removed some 2,100 tons 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."