Iranian Navy Says It Seized an Oil Tanker Off the Coast of Oman

Iran’s Navy said it had seized a vessel loaded with crude oil off the coast of Oman on Thursday after an armed group wearing military-style uniforms and black masks boarded the ship.

The vessel, previously named the Suez Rajan, was seized last year by the U.S. government over allegations that it was carrying Iranian oil in violation of American sanctions. The ship eventually unloaded the oil and continued to sail, but under a new name, St. Nikolas.

The ship was seized off the city of Sohar on Oman’s northern coast, near the Strait of Hormuz, according to a British government advisory group, the United Kingdom Maritime Trade Operations.

“Unknown voices” were heard over the phone, along with the captain’s voice, according to the advisory group, which sends maritime security information to merchant vessels. The ship then changed course to head toward Iranian territorial waters, and communication was lost, the group said.

Dimitris Roulias, a spokesman for Empire Navigation, based in Athens, said it had lost contact with the St. Nikolas, a vessel it manages, on Thursday morning. The vessel had departed from the Iraqi port of Basra and was headed to the Turkish port of Aliaga.

Ambrey, a maritime risk firm, said that the tanker was heading in the direction of Bandar-e-Jask, Iran, before its location information was turned off.

“There have been many efforts to establish communication, but with no success,” Mr. Roulias said. “There is no information on what exactly is happening on board the vessel.”

The vessel has a crew of 18 Filipino nationals and one Greek national, he said. He said he had no information about the ship’s current location and could not confirm how many people had boarded the vessel.

The incident came after weeks of attacks on commercial ships in the Red Sea, located on the other side of the Arabian Peninsula, where an Iran-backed Yemeni group, the Houthi militia, has pledged to prevent any vessels from reaching Israel until it ceases its bombardment of Gaza.

On Wednesday, U.S. and British officials said they intercepted one of the largest barrages yet of drones and missiles fired from an area in Yemen controlled by the Houthis. The Houthis have refused to back down, despite threats of retaliation by the U.S. and its allies.

In past periods of heightened tensions in the Middle East, ships in the Gulf of Oman have been targeted, including several attacks in 2019 that American officials attributed to Iran, which is just 100 miles across the gulf from Sohar.

There was no immediate statement from the government of Oman, which maintains friendly ties with both Iran and the United States, serving as a mediator between them.