A Nigerian shipowner has denied reports that six crew members died in an unexplained accident on a tanker off Lagos.

The Nation reported that the deaths of the unidentified seafarers were confirmed by Nigerian authorities at the weekend.

Maritime Bulletin reported that the 26,200-dwt Halima (built 2002) was undergoing tank cleaning work at the time, raising the possibility of asphyxiation as a cause.

The Nigeria-flag tanker had left Monrovia in Liberia on 27 January and remained anchored off Lagos on Monday morning.

A statement from the Nigerian Navy vessel Beecroft confirmed a distress call was received from the ship through the Western Region Control Centre (WRCC) of Falcon Eye, the navy’s maritime domain awareness facility.

After analysing the tanker’s coordinates and discovering it was positioned southwest of the Lagos Fairway Buoy, a rescue party was sent from the naval vessel.

“The victims were evacuated to Mekwe Jetty, Victoria Island, where the owner of the vessel moved them to the Military Hospital in Ikoyi for medical treatment,” the statement added.

Vessel owner Red Star Oil & Gas said there had been no fatalities, however.

The company told TradeWinds it could not reveal details of exactly what happened on the ship due to “ongoing internal and regulatory authorities investigations.”

The commander of the Beecroft, rear admiral Abdul-Rasheed Malami Haruna, advised crew members to observe the highest level of safety while operating at sea, in line with international best practices.

He also assured the public of the country's commitment to the safety of seafarers working in its waters.

The tanker has insurance cover through American Steamship.

There are no port state control detentions on its record.