Costa Concordia Shipwreck Anniversary Service

Robert Nisbet, in Porto Santo Stefano

Survivors of the Costa Concordia shipwreck - and relatives of the 32 people who died when the cruise liner ran aground - have marked a year since the disaster with a series of events near the rusting wreckage.

The unveiling of memorials to the victims, a minute's silence and a mass in their honour at the church on the island of Giglio, where many of the survivors were treated after they were forced to abandon the listing ship, were held to recall the tragedy.

The first event of Sunday's day-long commemoration was the return to the sea of part of the massive rock that tore into the hull of the 112,000-ton ocean liner on January 13, 2012, and remained embedded as the vessel capsized.

A crane on a tug lowered the boulder onto the reef off Giglio. Affixed to it was a memorial plaque. Survivors and relatives of the dead embraced as they watched the ceremony from another boat.

The commemoration will also include a symbolic launch of lanterns into the sea at the moment the ship hit the rock which gouged a 230ft gash in the hull.

The 952ft-long cruise liner, which is twice the weight of the Titanic, hit Le Scole reef after the captain sailed within a few hundred yards of the island.

Captain Francesco Schettino is under investigation for manslaughter, causing a shipwreck and abandoning the vessel before all the passengers were evacuated.

He remains under house arrest, but has not been formally charged.

The ship had 4,252 passengers and crew and was on a six-port cruise when the captain decided to stage a "sail-past" to honour a retired seaman who lives on Giglio, off the coast of Tuscany.

Captain Schettino insists the cruise company had permitted the route on several other occasions, and that his actions in steering the stricken ship onto an underwater ledge spared the lives of many others.

Some survivors, who were offered 11,000 euros  (£9,100) compensation by Costa Cruises, were asked not to attend Sunday's event because the small island is already crowded with victims' relatives and media.

Many are now seeking civil claims against the American parent company Carnival.

The operation to right the ship is now running over budget and behind schedule because of the enormous technical challenges faced by the salvage team.

Over 400 engineers are planning to attach giant metal floats to either side of the ship - some 11 storeys high - before using a series of pullies to slowly stand the vessel.

She will then be towed to a port, possibly in Sicily, where it could take two years to dismantle the ship and sell remnants for scrap.

The salvage cost, to be mostly covered by insurance payouts, has now risen from 300m euros (£248m) to 400m euros (£331m), and is described as the biggest operation of its kind ever attempted.

The delay has been caused by environmental fears, the hard nature of the bedrock, and the position of the ship which must now be slowly shifted on its axis.

It should be refloated by the end of September at the latest.