An oil tanker that was stormed by special forces off the Isle of Wight after a suspected hijack attempt had been denied port access by France and Spain to disembark seven stowaways in the days leading up to the incident. The men were detained when the Special Boat Service (SBS) stormed the Liberian-registered tanker on Sunday after it was feared the crew was no longer fully in charge. But the Guardian understands French authorities had previously refused the Nave Andromeda permission to berth and disembark the stowaways while Spanish authorities denied the tanker access to Las Palmas port. According to the shipping newspaper Lloyd’s List, vessel-tracking data shows the tanker sailed from Nigerian waters on 5 October and spent 24 hours off the French coast near Saint-Nazaire from 20 October, before sailing north. It then spent two days off the Spanish and Portuguese coasts before arriving in waters off the south coast of England on 25 October. The International Maritime Organization guidelines on stowaways state that shipmasters are required to notify authorities of the existence of stowaways at the next port of call, as well as taking steps to establish their identity and where they embarked. Shipmasters must also ensure the security, general health, welfare and safety of stowaways until disembarkation, as well as ensuring they are treated humanely. The Nave Andromeda’s operator, Navios Tankers Management, said the stowaways “illegally boarded” the tanker in Lagos. It also thanked the UK authorities involved in the operation “for their timely and professional response”. A statement from the company said the master of the ship had become “concerned for the safety of the crew due to the increasingly hostile behaviour of the stowaways” as they approached the UK. Sources told Lloyd’s List that the master remained in control at the bridge and the chief engineer was locked in the engine room. The 228-metre oil tanker had been due to dock in Southampton on Sunday to pick up a cargo of petrol but its course in the Channel became erratic, prompting calls for an intervention as it passed the south-east edge of the Isle of Wight. The SBS used two Royal Navy Merlin and two Wildcat helicopters to take control of the tanker. Hampshire police said all 22 crew members were safe and well, and the vessel has been detained while officers carry out investigations. The stowaways have been arrested on suspicion of seizing or exercising control of a ship by use of threats or force under the UK’s Aviation and Maritime Security Act 1990.