The prosecutor's office said survivors of the shipwreck off the Tuscan coast would be questioned in the investigation, as it seeks to establish whether there are criminal liabilities in the case and assess psychological damage caused by the accident.

Four French nationals were among the 17 casualties whose bodies were recovered after the 114 500-tonne Costa Concordia hit a rock.

Some 15 people, two of them French, are still unaccounted for and a criminal investigation is under way in Italy, with the cruise ship's captain, Francesco Schettino, facing charges of multiple manslaughter and abandoning ship before the evacuation of more than 4200 passengers and crew was complete.

Costa Cruises has offered 11 000 euros (about R111 000) in compensation to each of the passengers aboard the liner, in a bid to limit the legal fallout of the accident, but that has not stopped a flurry of legal complaints being filed around France.

There were 462 French people on board the cruise. After meeting last week with representatives of a victims' association based near the city of Bordeaux, the French justice ministry took a decision to group all the French complaints together.

The French inquiry could run in parallel with the Italian inquiry or be used to complement it.

Costa Cruises is a unit of Miami-based Carnival Corp., the world's biggest cruise operator.