All 77 passengers and crew were forced to flee the Jean Nicoli ferry in the Port of Marseille, after an explosion occured in the seaport of Marseille. The incident happened on Sunday, 31 July, on the 9am service to Sardinia.

French security services are on high alert, and extra army and police troops have been station in seaport towns, after Islamic State (Isis) attacks after the Bastille Day lorry attack in Nice, which killed 84 people, and the execution of a priest in Normandy.

"We do not understand what happened. It is not known if the explosion took place in or on the ship… no one will go up on board before we have a specialist dog in explosive detection," said a police senior officer in a report by La Provence.

Following the explosion, divers from the French coast guard inspected the hull of the ship, but no cracks were detected.

The cause of the explosion is still unknown although one explanation as this it was a bomb from World War II. "We are moving towards an accidental explosion, we think it's an ammunition - what type of ammunition is not clear yet - which must date from the second war, that exploded in depth the passage of the boat," said Jean-Jacques Fagni, deputy prosecutor of Marseille.

Crew members on board the Jean Nicoli ferry told AFP: "I was in the cabin, and there was the sound: 'boom',said two maintenance workers. "Traces that seem to support an explosion on the bottom."