ROME (Reuters) - Salvage crews began preliminary work this week on preparations to refloat the half-submerged Costa Concordia cruise liner in what is set to be the biggest ever operation of its kind.

A barge has moved next to the liner and the ship's radar has been removed from the upper deck. The swimming pool slide and the large yellow funnel will be taken off in coming weeks, salvage workers and local officials said.

The 290-metre-long (951 feet) cruise liner, operated by Carnival Corp's Costa Cruises unit, capsized off the Tuscan island of Giglio after hitting rocks on January 13. At least 30 people died and two are still unaccounted for.

"The preliminary work has begun before the ship is stabilized, which will happen in the next few months," Mayor of Giglio, Sergio Ortelli, said on Wednesday.

U.S. firm Titan Salvage, owned by Crowley Maritime Corp, and Italian firm Micoperi are handling the refloat and removal of the ship, which is set to cost at least $300 million and last about a year.

The vessel is expected to be stabilized by the end of August to prevent it shifting down the rocky ledge it is resting on and plunging into the deep waters of the surrounding marine reserve.

Two cranes attached to an underwater platform beside the 114,500 metric ton (126,215 ton) ship will then pull it upright, helped by the weight of big water-filled tanks that will be fitted on the part of the ship above water.

Once upright, more tanks will be fitted to the other side of the hull. They will then be emptied and filled with air to refloat the huge liner, which will be towed to an Italian port and broken up.

The ship's owner has said guarantees for the local tourist industry and protection of the environment during the salvage operation will be key priorities.