Jeremy Hunt warned Iran yesterday that it was choosing a “dangerous path” after it seized a Scottish-run oil tanker in the Persian Gulf.
The Foreign Secretary said Britain would take “robust” action if the Stena Impero was not released.
The Swedish-owned vessel, which is managed by Clydebank firm Northern Marine Management, was surrounded in the Strait of Hormuz on Friday before heading into Iranian waters.
A second vessel, The MV Mesdar, run by Glasgow-based Norbulk UK, was also boarded by armed guards in the critical shipping lane but was released on Friday.
Iran’s Guardian Council, a powerful constitutional watchdog, said yesterday the seizure of the British-flagged Impero was in response to the UK’s role in seizing an Iranian tanker, the Grace 1, in Gibraltar earlier this month.
The Fars news agency quoted council spokesman Abbas Ali Kadkhodaei as saying that “the rule of reciprocal action is well-known in international law”.
Mr Hunt said yesterday the “action in the Gulf shows worrying signs Iran may be choosing a dangerous path of illegal and destabilising behaviour after Gibraltar’s legal detention of oil bound for Syria”.
He added: “Our reaction will be considered but robust.”
Iran’s state-run IRNA news agency added the tanker was seized after it collided with a fishing boat and failed to respond to calls from the smaller craft.
The vessel’s owners said it was fully complying with regulations and was in international waters when it was approached.
It said there were no reported injuries among the 23 crew members, who are Indian, Russian, Latvian and Filipino. The UK government has advised UK shipping to stay out of the area.
The SNP condemned the seizure of the British-flagged tanker as “unacceptable” and called for “cool heads and a multilateral response”.
SNP Westminster Foreign Affairs spokesperson Stephen Gethins MP said: “Iran’s actions are completely unacceptable and must be condemned.
“These latest developments are incredibly concerning and the UK must work with our partners in the international community to find a resolution and call out Iran for its actions.”
France expressed its “full solidarity” with Britain, adding that it was “very concerned” by the seizure of the tanker. Germany has also voiced concern.
Meanwhile, UK motorists have been warned tensions in the Gulf could result in price hikes at fuel pumps.
The Strait links the Middle East’s crude oil producers with key markets around the world. A fifth of all oil supplies pass through the area.
Bob Sanguinetti, from the UK Chamber of Shipping, said there is “no alternative route in and out of the Gulf”.
The AA’s Luke Bosdet said: “Our big fear is that the cost of fuel may get worse if the tensions continue.”
The US blamed Iran for attacks on tankers in the key shipping area since May. Tehran denies the accusations.
On Friday, the US claimed to have destroyed an Iranian drone in the Gulf.
The same day, Gibraltar granted a 30-day extension to allow authorities to continue detaining the Grace 1, which was seized by British authorities on suspicion of carrying oil to Syria in breach of EU sanctions.
Iran has threatened to close the strait if its vessels are blocked from trading oil as a result of the Trump administration’s decision to re-impose tight sanctions.
Approximately three British-flagged ships travel through the Strait of Hormuz each day with around two dozen more present in the Persian Gulf area as a whole.
The Gulf region is home to over 10,000 ex-pat Scots.
Five flights leave Scotland every day for airports in Doha in Qatar and Dubai.
Aviation security analyst Tim Ripley said: “The area is a tinderbox at the moment and matters are approaching a crisis situation.”
Jeremy Hunt said the Stena Impero was sailing in Omani waters when seized. Parliament will be updated on the crisis tomorrow.
The Government’s emergency Cobra committee met again yesterday to discuss how to secure the safety of UK and international shipping in the Strait of Hormuz.
Hunt posted on Twitter: “Reaffirmed UK desire to de-escalate but confirmed Stena Impero was seized in Omani waters in clear contravention of international law.”