The ship was in Omani territorial waters and was “exercising the lawful right of transit passage in an international strait”, Britain’s UN mission wrote in a letter to the United Nations Security Council.
The seizure of the Stena Impero by Iran’s Revolutionary Guard was seen as a major escalation after three months of confrontation.
Latest developments:
- Foreign Secretary Jeremy Hunt has told his Iranian counterpart he is “extremely concerned” by the seizure. He also warned there will be “serious consequences” if the tanker is not released
- Iran’s state media has released footage showing the moment the country’s Revolutionary Guard seized the British-flagged ship
- UK government’s emergency Cobra meeting discussed guaranteeing security of shipping
- Stena Bulk, which operates Stena Impero, is making a formal request to visit the vessel. The company has been told its crew members are in “good health”
- The Iran Revolutionary Guard said it managed to bring the Stena Impero to Iranian shores despite “resistance and interference” from a British warship
- But Defence Secretary Penny Mordaunt told Sky News that HMS Montrose was 60 minutes away from being able to help
- Iranian authorities have said crew members may be interviewed by authorities on “technical matters”
- Labour leader Jeremy Corbyn has called for the British-flagged tanker and its crew to be released – but said all sides must show restraint as escalation risks a “deeper conflict”
- The European Union has warned the development “brings risks of further escalation”
The letter comes as the government plans to impose sanctions on the Iranian regime in response to the seizure.
Foreign Secretary Jeremy Hunt is expected to use a statement in the Commons to announce diplomatic and economic measures – including potential asset freezes – according to The Telegraph.
The UK could push for the UN and the European Union to reimpose sanctions on Iran which had been lifted in 2016 following the nuclear deal.
Defence Secretary Penny Mordaunt earlier described the seizure as a “hostile act”.
But the letter, which was also sent to UN secretary-general Antonio Guterres, said Britain’s priority is to de-escalate and it does “not seek confrontation with Iran”.
However, it added, “it is unacceptable and highly escalatory to threaten shipping going about its legitimate business through internationally recognised transit corridors.”
The UK has called on Iran to release the tanker and told the Security Council it was working to resolve the issue diplomatically.
Iran suggested the seizure was in response to the UK’s role in detaining a tanker carrying Iranian oil earlier this month, despite initially saying the British-flagged tanker was held because it collided with an Iranian fishing boat.
A spokesperson for Iran’s Guardian Council said “the rule of reciprocal action is well-known in international law”.
Iranian state media earlier released footage showing the moment the Stena Impero was seized.
In the footage, armed troops wearing ski masks are seen rappelling onto the ship’s deck from a helicopter hovering overhead.
