Italian divers on Tuesday gave up their search on the wreck of the Costa Concordia, in which 32 people are feared to have died, as workers prepared to start pumping out fuel to avoid an oil spill.

"We have definitively stopped the underwater search inside the ship," said Luca Cari, fire brigade spokesman on the island of Giglio, explaining that conditions inside the giant half-submerged liner were becoming too risky.

"The conditions are no longer acceptable," he told AFP.

The civil protection agency, which has been overseeing rescue efforts following the January 13 disaster, said in a statement it had contacted the families of the missing and foreign embassies involved to explain its decision.

It added that rescuers would continue to inspect the above-water part of the liner and use specialist equipment to check for corpses on the sea bed in an 18-square-kilometre (seven-square-mile) area around the wreck.

The 114,500-tonne Costa Concordia with more than 4,200 people aboard ran aground on rocks off Giglio and lurched on to its side as passengers were settling down to dinner shortly after the start of a Mediterranean cruise.

Seventeen bodies have been recovered from the sea and the wreck and 15 people remain missing.

The search has had to be suspended several times due to choppy seas and small movements of the wreck, which sparked fears that the massive ship could slip off the rocky shelf it is resting on and sink entirely.

Divers have described tricky conditions inside the ship, with corridors cluttered with furniture and turbid waters. Dives have been limited to a maximum of 50 minutes, making it difficult to penetrate far into the vessel.

A spokeswoman for the civil protection agency said the last unidentified body was "very probably" that of a German woman born in 1945 but added that the formal identification had not yet been made.

Meanwhile Pier Luigi Foschi, the chief executive of operator Costa Crociere, part of US-based giant Carnival Corp, told a Senate committee hearing that fuel pumping from the ship would start within the next 24 hours.

"We believe that the wreck can no longer be put in use," he said of the ship, which cost 450 million euros (590 million dollars) to build and was launched in 2006.

Environmentalists fear that the 2,380 tons of heavy fuel oil in the Costa Concordia's tanks could begin leaking out into the area's pristine waters.

"The first operation will be to empty the ship, the second to clean up the wreck and the third to move the ship, which will be a truly enormous operation that has never been done before," Foschi told senators.

Island residents concerned about the impact on tourism have called for the ship to be removed quickly and have launched a protest after the civil protection agency said it would take up to a year.

The head of the consumer association group Codacons, which is taking part in a class action lawsuit against Carnival Corp and Costa Crociere, said it had requested that the wreck be removed within 30 days.

The head of Costa Crociere's crisis unit, Roberto Ferrarini, who was alerted by the captain on the night of the disaster, also spoke to investigators on Tuesday, the first executive to be heard by prosecutors.

Captain Francesco Schettino and first officer Ciro Ambrosio are accused of manslaughter and abandoning ship.

A medical officer on the ship, Gianluca Cosentino, said in an interview published on Tuesday that Schettino seemed "shaken and no longer lucid" on the night of the disaster and was not coordinating rescue operations as he claimed.

"I was very surprised to see Schettino in civilian clothes in the harbour at around half past midnight," Cosentino told Il Mattino daily.