1. Towing operations carried out under the conditions set out in articles 257 to 259 above are also reserved for the French flag:
a) within the ports or territorial waters of mainland France and the French overseas departments ;
b) between the ports of one of these territories;
c) between the ports of Guadeloupe, French Guiana and Martinique;
d) Between the ports of Mayotte and Réunion.
2. Voluntary stopovers or layovers abroad do not have the effect of modifying the nature of these operations, unless it can be justified that during the said stopovers or layovers, the towed vessel has loaded or unloaded goods representing together, in terms of charter tonnes, at least one third of the net tonnage or has undergone repairs the cost of which exceeds 0.46 euro per tonne of total gross tonnage.
3. However, the foreign flag may be allowed to carry out the aforementioned towing operations in the event that there is no French tug available or sufficient on site or in French ports closer than the home ports of the foreign tugs that may be required.
4. Foreign tugs are permitted to enter French ports, either when they are towing vessels or barges from a foreign port or from the open sea beyond the limit of territorial waters, or when they are coming to take vessels or barges in tow in order to drive them into a foreign port or beyond the limit of territorial waters, their operations within the ports being limited to driving or taking the vessel to its berth.