Iranian navy seizes oil tanker in Gulf of Oman

LONDON -- An oil tanker was seized by the Iranian navy in the waters between Iran and Oman on Thursday, according to state media.

Iran's state-run news agency IRNA published a brief story confirming the seizure by the navy but did not identify the vessel.

Empire Navigation, the manager of the ship, later identified it as the St. Nikolas, a Marshall Islands-flagged, Greek-owned vessel. Empire Navigation said it has had no contact with the ship since 6:30 a.m. Athens time.

The company said its main concern was the 19-member crew, comprised of 18 Filipinos and one Greek national.

"Empire Navigation as the manager of the vessel has notified the pertinent authorities from the first moment and is in close and constant cooperation with them as well as with the crew members' next of kin," the company said in a statement.

In 2023, the same tanker was seized by the United States in a sanctions enforcement operation as it was taking Iran oil to China. Then called the Suez Rajan, it was later renamed to the St. Nikolas.

White House spokesperson John Kirby condemned the seizure of the oil tanker and called on Iran to "immediately release the ship and its crew."

"Its provocative and unacceptable actions need to stop," he said.

Earlier Thursday, the United Kingdom Maritime Trade Operations, or UKMTO, said it had received a report of several gunmen boarding a ship in the Gulf of Oman.

Four to five "unauthorized" individuals who were "armed" and "wearing military style black uniforms with black masks" reportedly boarded the vessel early Thursday in an area some 50 nautical miles east of Sohar, a port city on Oman's northern coast, according to a notice from the UKMTO, which is part of Britain's Royal Navy and provides warnings to sailors in the Middle East.

The UKMTO said that the ship had reportedly "altered course towards Iranian territorial waters and communications with the vessel have been lost."

"Authorities are investigating," the UKMTO added. "Vessels are advised to transit with caution and report any suspicious activity to UKMTO."

The incident happened amid high tensions in the nearby Red Sea, where Yemen's Iran-backed Houthi rebel group has been attacking international ships for weeks.

ABC News' Will Gretsky and Justin R. Gomez contributed to this report.