A UN-backed tribunal has ordered Nigeria to release a Swiss tanker, its crew and cargo detained there since January 2018.

The International Tribunal for the Law of the Sea (ITLOS) voted 17 members to four to free ABC Maritime's 7,600-dwt San Padre Pio (built 2002), which had been accused by the Nigerian navy of entering its territorial waters to engage in illicit ship-to-ship transfers of gasoil.

It has 5,000 tonnes of cargo and 16 Ukrainian crew on board, but the master and three officers have remained in Nigeria.

Switzerland must now post a bond of $14m to secure its release, ITLOS said.

It will also ensure that four officers are available and present at any criminal proceedings in Nigeria, if an Annex VII arbitral tribunal finds that the arrest and detention of the tanker, its cargo and crew does not constitute a violation of the United Nations Convention on the Law of the Sea.

The ship's captain, Andriy Vaskov, had 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.

Rights prejudiced?

The tribunal considered that the arrest and detention of the ship “could irreparably prejudice the rights claimed by Switzerland relating to the freedom of navigation and the exercise of exclusive jurisdiction over the vessel as its flag State if the Annex VII arbitral tribunal adjudges that those rights belong to Switzerland,” it said.

"There is a risk that the prejudice to the rights asserted by Switzerland … may not be fully repaired by monetary compensation alone,” it added.

The tribunal noted that the tanker "has not only been detained for a considerable period of time, but also that the vessel and its crew are exposed to constant danger to their security and safety."

It recognised Switzerland’s argument that bunkering activities carried out by San Padre Pio in the exclusive economic zone of Nigeria are part of the freedom of navigation and “that it has exclusive jurisdiction as the flag state over the vessel with respect to such bunkering activities”.

However, it also noted Nigeria’s argument that “it has sovereign rights and obligations … to exercise its enforcement jurisdiction over the bunkering activities in question in its exclusive economic zone”.

ITLOS said the 16 crew members were initially moved to a prison and charged with “conspiring to distribute and deal with petroleum product without lawful authority or appropriate license, and with having done so with respect to the petroleum product onboard."

The charges were later amended to apply only to the master, three officers and the vessel.

These four were released from jail and returned to the vessel upon the provision of bail on 13 April.