Survivors and victims' relatives began to arrive on Giglio for a commemoration on Sunday for the 32 passengers and crew who perished that night on a ship twice the size of the Titanic.

"It's not easy to return," said Kevin Rebello, whose brother was a waiter on the Costa Concordia and is still officially reported as missing.

"I was looking at the ship when I was coming in on the ferry. It brought back memories of those days, I have still not found peace," he said.

The liner crashed into a group of rocks just off Giglio, veered sharply and keeled over just as many passengers were sitting down for supper on the first night of a Mediterranean cruise.

Salvage workers have been labouring around the clock for months to stabilise the wreck and eventually refloat it and tow it away in an operation that has never been attempted before.

The removal has been hit by delays but the head of Italy's civil protection agency, Franco Gabrielli, said it would happen by September at the latest.

"The programme envisages the definitive removal by September," Gabrielli told reporters on the island, underlining that the operation was "exceptional".