FUJAIRAH/TOKYO A Japanese supertanker that reported suffering an "explosion" near the Strait of Hormuz oil shipping route may have hit a submarine or a mine, UAE port officials examining the ship said on Thursday.
Damage to the massive crude carrier's hull suggested a collision, although the nature of the incident early on Wednesday was under investigation.
"What we know is some collision happened. We don't know what it was," said Captain Mousa Mourad, a general manager at the UAE port of Fujairah.
"It's possible that it could be a submarine collision, or that it could be a sea mine," he said.
A Reuters reporter taken to see the damaged supertanker, the M.Star, said there was a very large, square dent and puncture marks on one side of the hull. Photographs also showed a lifeboat missing and smashed windows and doors.
Divers from a Dubai-based marine repair firm were dispatched to inspect the crude carrier, which was moored off Fujairah.
Speculation over what might have happened to the ship has included a rogue wave, an aborted hijacking, an internal blast of some kind or a collision with a submarine.
"It could also have been the bull nose end of a jetty at one of the loading ports where the tanker may have come into contact," said John Dalby, chief executive of maritime security company MRM.
The incident took place near the Strait of Hormuz, gateway to the oil-producing Gulf, bordered by Iran and several hundred kilometers north of where Somali pirates have hijacked supertankers over the past two years, including a South Korean tanker bound for the United States in April.
No oil leaked from the supertanker and the Strait remains open, with normal traffic flows, port officials said.
Mitsui O.S.K. Lines Ltd (9104.T), owner of the world's second largest oil tanker fleet, said on Thursday it had hired a Dubai-based specialist on military attacks to help investigate damage to the 333-meter (1,100-foot) supertanker laden with oil for Japan.
Warships from the U.S. Navy and other nations patrol the region, but were not near the supertanker at the time of the incident early on Wednesday, a spokesman for the U.S. Fifth Fleet based in Bahrain told Reuters. <ID:LDE66S12I>
U.S. nuclear submarines have been in two collisions in the busy Strait of Hormuz since 2007, one involving a Japanese supertanker and the other a U.S. warship.
Mitsui O.S.K.'s general manager of tanker safety, Masahiko Hibino, said the crew reported hearing an "explosion" but the company could not definitively say there had been an attack on the ship. Nor could it rule out the possibility of an internal explosion.
A company spokesman said Mitsui was aware of a Lloyd's List report speculating the damage may have been caused by a grenade attack, but was unable to say whether this was true.
Mitsui also rejected suggestions from officials in the UAE, Oman and Iran on Wednesday the ship may have hit a rogue wave.
The 31-strong crew, including one man injured in the incident, remain on board and are expected to set course for Japan once inspections and repairs are completed in about a week.
The tanker, bound for Chiba, near Tokyo, is carrying around 2.3 million barrels of Qatar Land and Abu Dhabi Lower Zakum crudes, industry sources say.
(Additional reporting by Raissa Kasolowsky and Amran Abocar in Dubai; Jonathan Saul in London; Writing by Jason Neely; Editing by Barbara Lewis and Alison Williams)