A damaged Japanese oil tanker is headed back to the United Arab Emirates where officials hope to determine what caused an onboard explosion.
Japan's transport ministry said the M. Star was passing through the Strait of Hormuz early Wednesday with about two million barrels of crude oil when the crew reported a blast.
Japan's Mitsui O.S.K. Lines said that despite the explosion, the ship's tanks did not rupture and that no oil is leaking.
The company also said the explosion blasted a lifeboat off the ship and damaged some of the starboard hatches. Crew members said one person on board saw a flash of light on the horizon just before the explosion.
The United States Navy's Fifth Fleet, based in the Gulf state of Bahrain, said the cause of the blast was unknown. But the ship's owner claimed the explosion was likely the result of an attack.
Some port officials in the UAE are blaming the damage on a large wave caused by an earthquake. The U.S. Geological Survey, which monitors earthquake activity around the world, said on Wednesday it did not record any quake in the area. A U.S. Geological Survey official said Iran reported a small 3.2 magnitude earthquake early Wednesday, but that the quake was too small and too far inland to have caused a wave capable of damaging a tanker.
Japan's transport ministry said Wednesday that the M. Star was on its way from the United Arab Emirates to the Japanese port of Chiba when it was rocked by the explosion.
The ministry has said the cause of the explosion is not clear and said the area is not known for commercial piracy. Officials said the Strait of Hormuz remains open for shipping.
About 40 percent of all oil shipped by tankers passes through the Strait of Hormuz. The waterway, near Iran and Oman, connects the Persian Gulf to the Arabian Sea.
Some information for this report was provided by AFP, AP and Reuters.