Switzerland has petitioned a UN tribunal to release an ABC Maritime tanker and senior crew detained in Nigeria since January 2018.
In a hearing at the International Tribunal for the Law of the Sea (ITLOS), it demanded that Nigeria "take all measures necessary" to ensure that the restrictions on the liberty, security and movement of the 7,600-dwt San Padre Pio (built 2002) be lifted immediately.
It wants to the ship re-supplied and crewed so that it can leave with its cargo and "exercise the freedom of navigation to which her flag state, Switzerland, is entitled under the convention."
Switzerland also demanded the release of the master and three other officers to allow them to leave Nigeria.
And it asked for the suspension of all court and administrative proceedings, and that Nigeria refrain from initiating new ones which might aggravate or extend the dispute.
Nigeria asked the court to reject Switzerland's demands.
The Nigerian navy had accused the ship, laden with 5,000 tonnes of cargo, and its 16 Ukrainian crew members of entering the country's territorial waters to engage in illicit ship-to-ship transfers of gasoil.
The ship's captain, Andriy Vaskov, told Ukrainian media that the ship had permission to move the 5,000 tonnes of cargo through Nigerian waters.
It was the ship's fifth entry into the country.
In April, Swiss media reported that the remaining crew members were dealing with "difficult conditions" in Port Harcourt, where the ship has been moored since its seizure.
The same month, pirates fired on the ship in an attempted raid. They fled when Nigerian navy guards fired back.
