The cost of salvaging the Costa Concordia has spiralled to more than €500 million ($742 million).

The cruise ship, which sank off the west Italian coast in January last year, killing 32 people, cost €450 million ($668 million) to build.

It is thought the operation to pull it upright will take place later this month. Huge steel compartments will then be attached to the vessel to help it refloat.

“The latest timing… envisages that the wreck will be removed by the [northern] summer of 2014,” the project website says.

The biggest-ever marine salvage operation is complicated by the fact that two bodies remain on the partly submerged ship.