DUBAI — A British warship tried but failed to prevent Iran’s Islamic Revolutionary Guard Corps from seizing a British tanker in the Strait of Hormuz last week, intercepted radio communications show, fueling a wave of recriminations in London on Sunday over who was to blame for the incident last week.
In recordings obtained by the shipping consultancy Dryad Global and posted on its website Sunday, a member of the Revolutionary Guard is heard ordering the British-flagged Stena Impero tanker to divert course toward Iran.
‘‘Alter your course,’’ the man says. ‘‘If you obey you will be safe.’’
A British naval officer interrupts, telling the Stena Impero that it has the right to proceed through the waterway.
‘‘Under international law your passage must not be impeded, obstructed, or hampered,’’ he says.
The British officer then addresses the Iranian: ‘‘Please confirm that you are not intending to violate international law by unlawfully attempting to board the MV Stena.’’
He spoke from the British frigate HMS Montrose, one of two warships sent to the Persian Gulf to protect British shipping after Iran threatened to seize a British tanker in retaliation for Britain’s detention of an Iranian tanker in the Mediterranean earlier this month.
Neither Britain nor Iran challenged the authenticity of the recordings.
Iran says it detained the Stena Impero for unspecified ‘‘violations’’ of maritime law.
A former head of the Royal Navy said the tanker should have been better protected before it was intercepted on Friday.
In London, British Defense Minister Tobias Ellwood pushed the criticism aside. The priority now, Ellwood said, must be to ‘‘de-escalate tensions’’ with Tehran after Iranian forces.
‘‘Our first and most important responsibility is to make sure that we get a solution to the issue to do with the current ship, make sure other British-flagged ships are safe to operate in these waters and then look at the wider picture,’’ he said on Sunday.
Asked by Sky News whether Britain had taken its ‘‘eye off the ball’’ and failed to defend ships in crucial waterways, Ellwood replied: ‘‘No, not at all.’’
Soon after the exchange was recorded, Iranian commandos wearing balaclavas brazenly descended from a helicopter by rope onto the deck of the tanker, as Iranian fastboats closed in by sea, video posted by Iranian media shows. No British warships were in sight.
On Sunday evening, Iran’s Press TV showed footage of the Stena Impero at the Iranian port of Bandar Abbas, flying an Iranian flag. There was no sign of its 23-member crew, most of whom are Indian nationals. Iranian media quoted Iranian officials on Sunday as saying the crew is safe.
The tanker’s seizure illustrates the challenge confronting the international community as it attempts to secure the safety of shipping in the Persian Gulf and the narrow Hormuz Strait that controls access to it. The United States has also sent naval reinforcements to the area, and is trying to encourage other allies to join it in a coalition to protect commercial shipping.
Iran, meanwhile, appears to be relishing the world’s unease, releasing videos and photographs showing the Revolutionary Guard acting unimpeded in the open seas and flying its flag over a confiscated British vessel. Hours before the interception of the British tanker, Iranian media posted what they said was drone footage of the deck of the USS Boxer, one of the US warships dispatched to secure the waterway.
A fifth of the world’s oil passes through the narrow, crowded strait. Many countries, including China, rely on the route for a far greater percentage of their energy needs.
Iranian Foreign Minister Mohammed Javad Zarif on Sunday warned Britain not to escalate the situation. In a posting on his Twitter account, he accused the US national security adviser, John Bolton, of seeking to drag Britain ‘‘into a quagmire.’’
‘‘Only prudence and foresight can thwart such ploys,’’ he tweeted.
The standoff comes as the British government and lawmakers are distracted with the finale of the leadership contest to succeed outgoing Prime Minister Theresa May, a race between Foreign Secretary Jeremy Hunt and former foreign secretary Boris Johnson.
Johnson is expected to win and enter 10 Downing Street on Wednesday afternoon — with the crisis with Iran waiting on his desk.
In a column in the Observer newspaper, the retired Admiral Allan West, a former first sea lord and chief of Naval staff, wrote that the British government’s warning that British-flagged vessels avoid the passage through the Persian Gulf was ‘‘not good enough.’’
‘‘We should have enacted control of shipping procedures, directing ships to assemble in safe areas and then taken them through in convoy,’’ he wrote.
‘‘Whoever the next prime minister is,’’ West wrote, ‘‘he is going to face a major international crisis as soon as he is in post. It cannot be ignored because of Brexit.
‘‘Some powerful groups in Israel, Saudi Arabia, and the United States want war and think a precision strike against key parts of Iran’s military capability would lead to regime change. They are wrong. It would lead to an open-ended war with catastrophic consequences across the region and the globe,’’ he added.
Britain’s seizure of an Iranian tanker near Gibraltar this month prompted Iran’s threats to seize a British tanker in retaliation.
Britain said it seized the Grace 1 because it was transporting oil to Syria in violation of European Union sanctions targeting Syria’s government. But the Iranian seizure of the Stena Impero has thrust Britain into the heart of the ongoing dispute between Washington and Tehran over the US withdrawal from the Iran nuclear deal and subsequent imposition of harsh new sanctions on Iran’s economy.
West’s critique that Britain was distracted by Brexit and the Conservative leadership contest was supported by the top story in the Telegraph newspaper: ‘‘Boris Johnson’s biggest dilemma if he enters No. 10 — what to do about Carrie Symonds?’’ The article explored whether the likely new prime minister would cohabitate with his girlfriend at the official residence.
Johnson is in the middle of a divorce with his second wife and dating Symonds, a former Conservative Party communications official.