4. (1) Where there is no Bangladesh flag vessel or flag vessel of the trading country concerned available for carriage of any cargo from or to Bangladesh, the Prescribed Authority may liberate the cargo for carriage by a third country f lag vessel. (2) Where the country to which or from which any cargo is to be carried is not served by Bangladesh f lag vessels and the f lag vessels of that country also do not serve Bangladesh, the Prescribed Authority may liberate the cargo for carriage by a third country f lag vessel.