Iran’s Islamic Revolutionary Guard Corps (IRGC) has announced the seizure of a British oil tanker in the Strait of Hormuz.

Update 5:21 p.m. ET: The Iranian regime has freed the second ship seized.

The IRGC, which was recently designated as a foreign terrorist organisation by the United States, is reported to have seized a vessel which reports identify as the Stena Impero (MMSI: 232010294) in the busy waterway, which links the Persian Gulf to the Gulf of Oman.

The move may have been retaliation for the recent detention of an Iranian tanker carrying crude oil to Syria by the British Overseas Territory of Gibraltar, situated at the mouth of the Mediterranean Sea on the southern tip of Spain.

Officially, the IRGC claims that “Stena Impero was stopped while passing through the Strait of Hormuz for not observing international marine rules and regulations”, according to the BBC.

“After being confiscated, the tanker was led to the shore and handed over to the Ports and Maritime Organisation for legal procedures and the required investigations,” the IRGC statement added.

IRGC: "This oil tanker named Stena Impero was stopped while passing through the Strait of Hormuz for not observing international marine rules and regulations" pic.twitter.com/KF3sQamqno — BBC Monitoring (@BBCMonitoring) July 19, 2019

The ship’s operator confirmed that their vessel was “approached by unidentifiable small crafts and a helicopter” in international waters — seeming to contract the IRGC’s claims — and that they are no longer able to contact it in the following statement:

2019-07-19 – 19.55 Stena Bulk and Northern Marine Management can confirm that at approximately 1600 BST on 19th July UK registered vessel Stena Impero (built 2018, 49,683 DWT) was approached by unidentified small crafts and a helicopter during transit of the Strait of Hormuz while the vessel was in international waters. We are presently unable to contact the vessel which is now heading north towards Iran. There are 23 seafarers aboard. There have been no reported injuries and their safety is of primary concern to both owners and managers. The priority of both vessel owner Stena Bulk and ship manager Northern Marine Management is the safety and welfare of the crew. Northern Marine Management has not been able to establish contact directly with the vessel since it was notified of the incident at approximately 1600 Today, 19th July 2019. We are in close contact with UK government authorities.

Britain’s Secretary of State for Defence Penny Mordaunt is being briefed on this situation, but so far the only comment from the Ministry of Defence is that they are seeking more information on the situation as a matter of urgency.

Deputy Assistant to the U.S. President Garrett Marquis commented that he was “aware of reports that Iranian boats seized a British oil tanker,” adding that this was “the second time in just over a week the UK has been the target of escalatory violence by the Iranian regime”.

Tensions between Iran and the United States have also been running high, with the Islamic Republic shooting down a U.S. drone in June, U.S. President Donald Trump narrowly averting a major strike on the country in retaliation, and an Iranian drone reportedly being shot down by a U.S. warship earlier today.

Update: A second tanker with possible U.K. ownership, the Mesdar, has reportedly broken off course for Saudi Arabia and headed north for Iranian waters. Shortly after these reports broke, U.S. defense officials confirmed the Mesdar was also hijacked by Iranian forces.

This story is developing…

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