Prosecutors in the Italian city of Bari put four more maritime officials under formal investigation yesterday as the charred Norman Atlantic ferry was towed into the port of Brindisi.

In addition to the ship’s captain and the head of the company that built the ferry, who are both Italian, the prosecutor’s office targeted two crew members and two representatives of the Greek ferry line Anek, which leased the ferry.

The blaze that broke out on Sunday has killed at least 11 people.

Italy says that 477 people were rescued, mostly by helicopters that plucked survivors off the top deck in gale-force winds and carried them to nearby boats.

Towing the ferry overnight across the choppy seas of the Adriatic took 17 hours.

Firefighters and a prosecutor were first to go aboard yesterday to search it in case there were any bodies on board and to begin the hunt for the cause of the blaze.

Prosecutors fear that unregistered migrants were smuggled aboard in lorries and might have perished in the flames and smoke.

Italian newspapers quoted Captain Argilio Giacomazzi as telling prosecutors that the crew did not follow his orders properly in lowering lifeboats and that the car deck had too many vehicles.

nAn Icelandic coastguard ship reported yesterday that it was towing a cargo vessel to Italy yesterday with about 450 migrants on board who had been abandoned by smugglers, leaving the vessel in rough seas without a crew.

Most of the migrants on the Sierra Leone-flagged ship, which set sail from Turkey, are believed to be Syrian.