Iran has warned the UK not to enter a “dangerous game” as plans to relieve a Royal Navy warship in the Gulf were escalated amid escalating tensions.

Downing Street raised concerns over Tehran’s threats to disrupt shipping in the region after HMS Montrose drove off Iranian patrol boats attempting to impede the progress of a British tanker.

The UK acted on Friday to bring forward plans to dispatch Type 45 Destroyer HMS Duncan to the region to relieve Montrose, PA understands.

POLITICS Iran
(PA Graphics)

Tensions rose after an Iranian tanker was seized off Gibraltar in an operation involving Royal Marines.

The vessel was suspected of violating EU sanctions by carrying a shipment of Iranian oil to Syria.

Gibraltar on Friday said the vessel’s cargo was confirmed by laboratory testing to be 2.1 million barrels of light crude oil.

Duncan, currently in the Black Sea, will relieve Montrose in the Gulf so the Type 23 frigate can undergo planned maintenance and crew changes, the Government confirmed.

HMS Duncan
HMS Duncan is a Type 45 air defence destroyer (Chris Ison/PA)

A spokeswoman said: “This will ensure that the UK alongside international partners can continue to support freedom of navigation for vessels transiting through this vital shipping lane.”

Duncan, a Type 45 air defence destroyer, is considered to be one of the most advanced warships in the world, according to the Royal Navy.

Foreign Secretary Jeremy Hunt said Britain wants to “de-escalate” the “serious” situation and that sending HMS Duncan was “about our responsibility to do everything we can to protect British shipping”.

He told BBC Radio 4’s World At One programme: “We have a responsibility to protect British shipping and, with our allies, to protect the waterways and seaways of the world, so we have to react according to the threats that we face.

“But this is not an Iran-specific issue – notwithstanding the broader tensions in the region – this is about Syria and about a breach of the sanctions against Syria, which of course is a country that Iran is active in.”

Montrose was forced to act against the patrol boats in the Strait of Hormuz as it attempted to “impede” the passage of BP-operated tanker British Heritage.

The Iranian Revolutionary Guard, which is thought to have been operating the patrol boats, denied the incident.

The move came as police in Gibraltar arrested the captain and chief officer of Iranian supertanker Grace 1, which was detained last Thursday.

Iranian Foreign Ministry spokesman Abbas Mousavi called for the release of the tanker, rejecting the allegations, as he issued strong words to the IRNA news agency.

“The documents and evidence and the contradictory remarks made by the British all indicate that London’s allegation, legally speaking, is not that significant and noteworthy unless they would want to enter into a dangerous game under the influence of the Americans with no end in sight,” he said.

A Downing Street spokeswoman spoke of the Government’s concerns in the region.

“We are concerned about the threats that they are making to disrupt shipping in the area and we have been urging them to de-escalate the situation in the region,” she told a Westminster briefing.

Along with Montrose, the Navy has four mine countermeasures vessels and the Royal Fleet Auxiliary Cardigan Bay logistics ship in the region.