The plot thickened after preliminary investigations of the damaged oil tanker pointed to a blast on board and outside the vessel. The Director-general of Fujairah port, Captain Mousa Murad, confirmed the blast, but did not say what caused it, while the tanker’s owners did not rule out a terrorist attack.

‘‘Preliminary investigations of the tanker, which is anchored at a distance of 12 nautical miles within the territorial waters of the UAE, revealed an explosion. We don’t know the reasons yet,’’ said Captain Murad. Yesterday, Omani officials had said a tidal wave from a quake could have rocked and damaged the vessel.

The impact of the blast tore open the sailors’ quarters and damaged the upper deck. ‘‘Repairs are underway in the damaged sections,’’ said Captain Murad.

Speaking to Khaleej Times from Bahrain, US Navy 5^th Fleet Media Officer John Fage said an explosion occurred on board and a life-boat was blown away. ‘‘We don’t have additional details about what caused the blast. We certainly know the starboard hatches were damaged,’’ he said.

The blast theory gained ground when earlier in Tokyo, Mitsui O.S.K officials stuck to their assessment of the incident: “There are some reports saying the tanker was hit by strong waves, but it’s quite unlikely.”

“We have not reached a conclusion, but we still suspect the tanker was hit by a blast,’’ newswires quoting company spokesperson Masahiko Hibino, said.

Wam quoted Director of Media Affairs and Government Communications at the Foreign Ministry, Sultan Al Ali, as saying  in a statement that the investigations by relevant authorities to determine the causes of the accident was still underway.

‘‘No casualties have been reported and there has been no oil spillage or pollution,’’ he added.

The vessel was transiting the Strait of Hormuz with two million barrels of oil loaded at Um Saeed, Qatar and Das Island, UAE. Thirty-one sailors were on board during the incident.

The strategic Strait  is an oil lifeline where 40 per cent of the world’s crude passes. It is estimated that around 17 million barrels of oil flow via the Strait per day, and Middle East crude accounts for 90 per cent of Japan’s total imports.

Any disruption or incident in the waterway, which is about 100km at its widest point, is viewed with concern in a region where tensions run high.

What could have damaged the tanker?

Here are some questions and answers on what may have caused the damage.

Could it have been pirates?

Piracy was ruled out, as the type of damage the tanker sustained did not bear the hallmarks of how seaborne gangs operated. The incident also occurred too far north from where pirates had been active in the past.

Pirates have used rocket propelled grenades in attacks in the Gulf of Aden and maritime sources said RPGs could not have caused that type of damage to the tanker.

What about an attack by a group?

Maritime sources have not ruled out the possibility of an attack but said there was still too little information to reach any definite conclusion.

“It is impossible to know immediately what happened. One scenario is that it could have been attacked, and other that it could have been a collision or an accident,” said Jonathan Wood, global issues analyst with consultancy Control Risks.

Was it an internal explosion inside the ship?

Some shipping sources speculated that the damage may have been caused inside the tanker itself but others said the picture taken of the vessel indicated it was caused from outside.

“If it was an internal explosion the hull damage would have been convex not concave shaped,” said John Dalby, chief executive of chief executive of maritime security company MRM.

A maritime source said separately, another scenario is that one or more storage tanks imploded due to the inadvertent creation of a vacuum inside them as a result of the mismanagement of pumps.

Could the tanker have struck a sea mine?

Maritime experts ruled out a sea mine as it would have caused damage underneath the tanker and there would have been hull penetration.

“This is not damage that I would associate with a mine or torpedo,” said Gibbon-Brooks, a former mine clearance diver and above water warfare officer with the Royal Navy.

Could it have collided with a submarine?

A Fujairah port official said on Thursday a submarine collision could have caused the damage.

“The damage is too uniform. It’s almost a perfect square which indicates a man-made object — it could have been a submarine,” said Dalby of MRM which provides risk assessments to companies.

 news@khaleejtimes.com