The Costa Concordia, which crashed off an Italian island in January, leaving 32 people dead, is to be refloated and towed away by a US-owned salvage company, the ship's owners said this weekend.

Titan Salvage was awarded the contract in partnership with Italy's Micoperi, which specialises in underwater construction and engineering.

"Work will begin in early May, subject to final approval from the Italian authorities and is expected to take about 12 months," Costa Crociere said in a statement.

The Costa Concordia ran into rocks off the island of Giglio with 4229 people on board including 3200 passengers from 60 countries on January 13.

"We are very pleased to announce another important step towards salvaging the wreck from Giglio island," Costa Crociere chief executive Pier Luigi Foschi said.

He thanked Smit Salvage of the Netherlands and Italian firm Tito Neri for pumping out fuel from the ship, completed on 24 March, and said that throughout operations environmental protection would have top priority.

"As was with the case with the removal of the fuel, we have sought to identify the best solution to safeguard the island and its marine environment and to protect its tourism."

Once floated, the wreck will be towed to an Italian port and dealt with in line with the requirements of the Italian authorities, Costa said.

When the main work is complete, the sea bottom will be cleaned and marine flora replanted.

The main operations base will be on the mainland at nearby Civitavecchia, to minimise any impact on Giglio's tourism and port activities, it sad.

Nine people are being investigated in relation to the disaster including the ship's captain, Francesco Schettino, and three Costa Crociere executives.