France, Jan. 25 -- The 249-metre tanker was escorted to the Gulf of Fos, near the oil terminal at the port of Marseille-Fos, where its 58-year-old Indian captain was taken into custody on Saturday evening.

The move came three days after an operation in which French marine commandos were airlifted onto the ship in international waters.

Judicial authorities in Marseille have now taken charge of the case, opening a preliminary inquiry into suspected flagging offences.

Investigators from the Toulon maritime gendarmerie's research section, working alongside the Marseille ship safety centre, are carrying out checks on board the vessel, particularly focusing on navigation documents and the "validity of the flag", according to the public prose...