ROME (AFP) - Prosecutors in the Italian port of Bari on Monday opened a criminal investigation into how the car ferry Norman Atlantic caught fire at sea during a crossing from Greece to Italy, as rescuers recover four more bodies from the icy waters.

As the Italian navy battled to complete the evacuation of the stricken ship, saving 391 people so far, Bari prosecutor Giuseppe Volpe announced a probe to examine whether negligence contributed to the disaster in which at least one passenger died.

The investigation will seek to establish how the fire started and why it was able to gain such force that passengers feared they would be burned alive or suffocated by thick smoke.

The Italian owner of the boat has insisted that the vessel was in full working order and had passed a technical inspection which included its firedoors on December 19.

One of the first survivors to arrive in Italy on Monday has alleged that the staff were clearly unprepared for dealing with an emergency and appeared to be unaware of how to organise an evacuation.

Four bodies were recovered from the water around the stricken Norman Atlantic on Monday, a day after the body of a 62-year-old Greek man was pulled from the heaving sea. At least one passenger - a Greek national - was previously confirmed to have died as a result of the disaster.

Overall, 391 people have been rescued from the ferry that was carrying 478 passengers and crew, Maritime Minister Miltiadis Varvitsiotis told reporters.