Tehran signals it will not release British-flagged tanker until UK frees one of its vessels

The British foreign secretary, Jeremy Hunt, is under intense pressure to join US-led plans for an international maritime protection force in the Gulf as signs grow that Iran is preparing for a long standoff over the British-flagged tanker it has detained.

As Tehran signalled it would refuse to release the Steno Impero until the UK released an Iranian-flagged ship seized off the coast of Gibraltar a fortnight ago, the British government faced accusations it had failed to sufficiently guard its shipping in the Gulf.

Adding to the tensions, the defence minister, Tobias Ellwood, said cuts had left the Royal Navy too small to manage Britain’s interests around the globe.

Theresa May will chair a meeting of the government’s emergency committee Cobra at 10.30am BST. As well as receiving the latest updates from ministers and officials, the meeting will discuss the maintenance of the security of shipping in the Gulf. Hunt is due to make a statement to MPs on Monday afternoon.

Iran crisis: what are Britain's options in tanker standoff? Read more

Senior Tory backbenchers including figures close to Boris Johnson, who is expected to become prime minister this week, are angry at the government’s reluctance to accept an offer from Washington to protect British vessels in the region. The capture of the Stena Impero on Friday was widely seen as an avoidable error for which ministers had ample warning.

Iain Duncan Smith, a former minister tipped for a cabinet post in a Johnson administration, said the government needed urgently to answer the charge that it had made an error. He said genuine questions had been raised about the UK’s contingency planning after the UK seized the Iranian tanker, Grace 1, on 4 July. “If something didn’t send an alarm signal that we needed to have serious assets or protection and convoying of our vessels in that area then I want to know why not.”

Duncan Smith said his sources had suggested Washington had invited the UK “to use US assets to support British shipping and they were not taken up at that point.” He said he wanted to know why additional UK assets were not speedily dispatched.

Timeline Recent tensions in the Gulf Show Hide Tensions between the US and Iran have soared in 2019, with Washington dispatching warships to the Gulf, and Tehran resuming higher uranium enrichment. The UAE says four commercial ships off its eastern coast 'were subjected to sabotage operations'. Yemen's Houthi rebels launch a drone attack on Saudi Arabia, striking a major oil pipeline and taking it out of service. Saudi Arabia subsequently blames Iran for the attack. A rocket lands near the US embassy in the Iraqi capital, Baghdad, without harming anyone. It's not clear who is behind the attack, but after the initial reports, Donald Trump tweets: 'If Iran wants to fight, that will be the official end of Iran. Never threaten the United States again!' Saudi Arabia says 26 people were wounded in an attack by Yemen's Houthi rebels on an airport in the kingdom's south-western town of Abha. Two oil tankers near the strategic strait of Hormuz were reportedly attacked in an assault that left one ablaze and adrift. 44 sailors were evacuated from both vessels and the US navy assisted. Iran’s Revolutionary Guards say they have shot down what they called a US 'spy' drone they claim was flying in in the country’s airspace. The US military confirm one of its drones has been taken down, but say it was in international airspace. Donald Trump reportedly gives approval for the US military to launch strikes on Iran in retaliation for the loss of the drone, before pulling back at the last minute. The Iranian and US presidents trade insults, with Hassan Rouhani suggesting that Donald Trump suffered from a “mental disorder” and Trump once more threatening Iran with “obliteration”. Iran summons UK ambassador over an incident off Gibraltar as Royal Marines seize a tanker, Grace 1, the UK suspects of carrying oil to Syria. The International Atomic Energy Agency, the body tasked with verifying Iranian compliance with the terms of the nuclear deal, verifies that Tehran has breached the agreed 3.67% limit for enriched uranium. The UK government says three Iranian boats were warned off by the frigate HMS Montrose after Iranian boats 'attempted to impede' a British oil tanker in strait of Hormuz. Tehran denies involvement. In a major escalation, Iran seizes the Stena Impero, a British-flagged tanker, off its coast. Iranian officials later make it clear that the capture was in retaliation for the capture of the Iranian supertanker Grace 1 earlier in July. Despite US attempts in the courts to prevent it, Gibraltar says it will free oil tanker at centre of the Iran row. Iran gives assurances the oil is not destined for Syria, where selling it would breach international sanctions against Britain accuses Iran of breaching those assurances after Tehran acknowledged the oil had been sold, and the reflagged tanker Adrian Darya 1, previously known as Grace 1, had reached its final destination after the ship was photographed off the coast of Syria.

Hunt is expected to announce limited sanctions directed against members of the Iranian Revolutionary Guards and to say that the UK is willing to join an international protection force on the right terms. It will also send air assets to the region.

On Sunday evening, the Foreign Office confirmed Hunt had spoken with his French and German counterparts who agreed that a “safe passage for vessels” through the economically significant Strait of Hormuz was “a top priority” for Europe.

The Foreign Office is seeking a diplomatic solution to the conflict but has advised all British-flagged ships not to enter the Strait of Hormuz.

Bob Sanguinetti, the chief executive of the UK Chamber of Shipping, said: “We must restore confidence in the security of ships passing through the strait, and if this necessitates the deployment of more naval vessels from the international community, we would welcome that.”

The Iranian government said the length of detention of the mainly Indian crew on Stena Impero depended on the degree of their cooperation. “We are required by regulations to investigate the issue,” Allahmorad Afifipour, the head of ports and maritime in Hormozgan province, told Iranian state TV.

Afifipour said all 23 crew members from the ship were “safe and in good health”. The ship’s owners have asked to visit the crew.

Iranian MPs meeting on Sunday welcomed the ship’s capture and made calls for the government to consider imposing tolls on all British and US shipping heading to the Strait, a move that would lead to naval confrontations since the strait is considered international waters.

Facebook Twitter Pinterest Satelite images appearing to show the Stena Impero (the red ship) being held in the port of Bandar Abbas, in southern Iran. Satelite image captured on 20 July at 11.33am local time. Photograph: Planet Labs Inc/Tanker Trackers

Iranian officials were explicit that the capture on Friday was in retaliation for the capture of Grace 1. The speaker of Iran’s parliament, Ali Larijani, said the British “stole and got a response” from the Revolutionary Guards.

Britain privately admits it worked in conjunction with the US in the capture of Grace 1 but says it had independent intelligence that the ship contained oil bound for Syria, in violation of EU sanctions. It says the ship could not have been stopped had it not entered Gibraltarian waters.

Q&A Why is the Gulf of Oman so important for shipping oil? Show Hide The strait of Hormuz, which provides passage from the Gulf of Oman to the open sea, is the most important gateway for oil exports in the world. With Iran on its northern shore, and the UAE and Oman on its southern shore, the US Energy Information Administration (EIA) calls it the world’s worst 'chokepoint' In 2016, 18.5m barrels of crude oil were transported each day through the strait of Hormuz, compared with 16m through the strait of Malacca, which runs between the Indonesian island of Sumatra, Malaysia and Thailand, connecting the Indian Ocean with the South China Sea. 5m barrels of crude oil are transported annually through the next largest chokepoint, the Suez canal. Phillip Inman

It is possible ministers underestimated the reaction, particularly since Iran did not attempt any reprisal when the British – unlike the French or Germans – blamed the Revolutionary Guards for an attack on two tankers last month.

One Whitehall source admitted the government had considered turning a blind eye, admitting that an unworthy part of him had thought: “Let this cup pass from my lips.”

Ellwood again demanded the release of the Stena Impero, a call echoed by Oman in whose waters the ship was captured.

Speaking on Sky News, Elwood also made a stark call for a reversal of defence cuts. He said: “If we want to continue playing a role on the international stage – bearing in mind that threats are changing, all happening just beneath the threshold of all-out war – then we must invest more in our defence.”

Britain has been nervous of the rules of engagement of the US’s long-touted plan for an international maritime security force, nicknamed Operation Sentinel. There is already a UN-endorsed anti-piracy operation off the coast of Somalia, while combined taskforces already operate in the Gulf, dedicated to security and fighting drug-smuggling.

There are also issues about the funding of any new larger operation proposed by US Central Command. But, most of all, Britain fears US-led convoys in the Gulf could by accident turn from something passive and defensive into something more volatile.

Javad Zarif, Iran’s foreign minister, said on Sunday that the US national security adviser, John Bolton, “having failed to lure Donald Trump into war of the century … is turning his venom against the UK in hopes of dragging it into a quagmire.”

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Iran’s ambassador to the UK, Hamid Baeidinejad, said on Twitter that Britain needed to contain “those domestic political forces who want to escalate existing tension between Iran and the UK well beyond the issue of ships”.

There is an awareness in Iranian circles that the a Johnson premiership could lead to the UK weakening its support for the nuclear deal from which Trump withdrew last year.

Meanwhile Iran said it had arrested 17 Iranian nationals allegedly recruited by the CIA to spy on the country’s nuclear and military sites. Some of them have already been sentenced to death, Tehran claimed.