An ABC Maritime product tanker under arrest in Nigeria was boarded by armed pirates at Bonny River inner anchorage in Nigeria on Monday.

Four attackers in a speed boat approached the Swiss-owned 7,600-dwt San Padre Pio (built 2012), which was seized by the Nigerian navy in January 2018 over unauthorised entry and illicit fuel trade.

Two managed to board and fired shots with automatic weapons towards the accommodation block.

Nigerian naval guards on board returned fire, prompting the men to flee the deck and escape in their boat.

The alarm was raised and the crew mustered in the citadel.

One guard was injured during the shooting and was given first aid by crew.

Two security boats responded and approached the tanker.

All seafarers were reported safe.

Legal action brewing

The Swiss AZ website said the incident was reported in an intelligence bulletin from the British security firm EOS Risk Group.

The IMB reported the attack but did not name the ship.

It was reported earlier this month that Switzerland is to take legal action following the seizure of the tanker.

Swiss media reported that talks had failed to secure its release.

It was held with 16 Ukrainian crew and about 5,000 tons of cargo aboard.

Captain Andriy Vaskov told Ukrainian media at the time that the tanker had permission from Nigeria to ship the cargo.

It was their fifth entry into the country with oil products.

The SonntagsZeitung newspaper said the case is now set to come before the UN-affiliated International Tribunal for the Law of the Sea.

“Switzerland should make full use of all means to safeguard its interests. The country considers that the seizure of the vessel constitutes a violation of international law,” the foreign ministry told the newspaper.

The ministry confirmed that four Ukrainian crew members remain stranded on the ship in “difficult conditions”.

The rest were allowed to leave the ship about six weeks after the incident.

The report says that the state, as underwriter of the tanker and its owner, stands to lose millions if the cargo goes undelivered.

The amount of the guarantee is not specified, the newspaper said.

ABC told TradeWinds the situation continued to be a matter for the Swiss authorities and it was not able to make any further statement.