Iran's army said it had seized a Marshall Islands-flagged oil tanker in the Gulf of Oman after it collided with an Iranian boat, injuring several crewmen, Iranian state media reported.

"Two members of the boat's crew are missing and several were injured due to the collision of the ship with the boat," an army statement said.

The U.S. Navy identified the vessel as the Advantage Sweet. According to Refinitiv ship tracking data, it is a Suezmax crude tanker that had been chartered by oil major Chevron (CVX.N) and had last docked in Kuwait.

Chevron said it is aware of the situation involving the Advantage Sweet and is "in contact with the vessel operator with the hope of resolving this situation as soon as possible," a spokesperson said.

The vessel's destination was listed as the U.S. Gulf of Mexico port of Houston, ship tracking data showed.

Its manager is listed as Genel Denizcilik Nakliyati AS. The Turkey-based company did not immediately respond to a request for comment.

The Marshall Islands Maritime Administrator said it was aware of the situation and was in communication with the vessel's owner/operator but declined to comment further.

"Iran's continued harassment of vessels and interference with navigational rights in regional waters are a threat to maritime security and the global economy," the U.S. Navy said, adding Iran has in the past two years unlawfully seized at least five commercial vessels in the Middle East.

The U.S. Navy added that after sending a P-8 Poseidon maritime patrol aircraft to monitor the situation, "we have since been able to determine the IRIN (Iranian navy) conducted the seizure".

Iranian authorities did not immediately respond to a Reuters request for comment.

About a fifth of the world's crude oil and oil products passes through the Strait of Hormuz, a narrow choke point between Iran and Oman which the Advantage Sweet had passed through, according to data from analytics firm Vortexa.

BOARDED VIA HELICOPTER

Maritime security company Ambrey said the vessel had been boarded via helicopter. "The vessel did not show any signs of conducting evasive manoeuvres prior to the incident," it said.

Munro Anderson, with maritime security company Dryad, said separately that Iran usually detained vessels for "leverage or signalling".

"The working hypothesis at the moment is that it could either be an arbitrary detention of a vessel by Iran in response to the U.S. sailing its first unmanned vessel through the region last week - as a show of force," he said. "Or, it could be in response to the sanctions on the 24th (of April) by the U.S. against personnel in Iran connected to the IRGC (elite Revolutionary Guards)."

Since 2019 there have been a series of attacks on shipping in the strategic Gulf waters at times of tension between the United States and Iran.

Iran last November released two Greek-flagged tankers it seized in the Gulf in May in response to the confiscation of oil by the United States from an Iranian-flagged tanker off the Greek coast.

Indirect talks between Tehran and Washington to revive Iran's 2015 nuclear pact with world powers have stalled since September over a range of issues, including the Islamic Republic's violent crackdown on popular protests, Tehran's sale of drones to Russia and acceleration of its nuclear program.

The U.S. Navy, whose Fifth Fleet is based at the Gulf island state of Bahrain, called on Iran to immediately release the tanker.

The ship issued a distress call during the seizure, the U.S. Navy statement said.

According to the International Maritime Organisation shipping database, the Advantage Sweet is owned by a China-registered company called SPDBFL No One Hundred & Eighty-Seven (Tianjin) Ship Leasing Co Ltd.