Theresa May will chair a Cobra emergency committee meeting following the seizure of a UK-flagged oil tanker in the Strait of Hormuz on 19 July 2019.

The Stena Impero vessel was surrounded by four Iranian vessels and a helicopter before being boarded then redirected from its passage to Jubail towards Iran.

Swedish company Stena Bulk , which owns the Impero, has confirmed the vessel was in full compliance with all navigation and international regulations.

In a letter to the United Nations Security Council president, UK representative Jonathan Allen said: “Current tensions are extremely concerning, and our priority is to de-escalate. We do not seek confrontation with Iran. But it is unacceptable and highly escalatory to threaten shipping going about its legitimate business through internationally recognised transit corridors.

“The impediment to the right to transit passage and seizure of the Stena Impero is contrary to international law. We call on Iran to release the Stena Impero, and are working to resolve the situation through diplomatic means.”

This latest incident follows an attempt by three Iranian vessels to impede the passage of a British oil tanker through the Strait of Hormuz on 11 July 2019.

Tensions between Iran and the UK have heightened after the seizure of a tanker suspected to be carrying Iranian oil to Syria by UK commandos offshore Gibraltar on 5 July 2019, described by an Iranian foreign ministry spokesperson as “tantamount to maritime piracy.”

The Strait of Hormuz is one of the world’s busiest oil routes and the only sea passage through the Persian Gulf.

In a statement, International Chamber of Shipping secretary general Guy Platten said: “We are extremely concerned about this latest development in the Strait of Hormuz, particularly in respect of the safety of seafarers. We call on all authorities to work together to seek a swift and transparent resolution to the situation and to ensure that crews are kept safe.

“Freedom of navigation is vital for global trade and we encourage all nations to uphold this fundamental principle of maritime law. In the 21st century, it is not acceptable for seafarers and ships to become pawns in any way, they must be allowed to operate in safety. We will be reviewing the situation and remain in contact with relevant authorities.”

The conflicts in the Strait have strained the relationship between Iran and the west,  exacerbating tensions created by Iran’s breaching of limits placed on its low-enriched uranium stockpiles in July 2019, as well as US officials attributing attacks on two oil tankers in the Strait of Hormuz in June 2019 and a number of attacks on tankers in May 2019 to the nation.