Relations between Britain and Iran seem to be the bleakest they have been for decades with the confrontation over the tankers and rising accusations and recriminations.

At the same time there is increasing sabre-rattling in the wider arena of the region with Donald Trump‘s administration sending troops back to Saudi Arabia and Washington and Tehran raising the tempo of mutual insults and threats.

In London the cabinet emergency committee, Cobra, met until the early hours of Saturday morning and in the evening came the news that British Airways was cancelling flights to Cairo for a week as a security precaution. It was not immediately clear if this was related to the situation in the Gulf, but the development added to the uncertainly and trepidation.

Jeremy Hunt, the foreign secretary, spoke to his Iranian counterpart, urging him to release the seized British vessel, Stena Impero. Mr Hunt charged that the seizure was illegal and unjustified and demanded that the ship and its crew is released immediately.

Mohammad Javad Zarif is said to have responded that what happened was in retaliation for the UK’s seizure of the Iranian tanker Grace 1 off Gibraltar on suspicion that it was transporting oil to Bashar al-Assad’s regime in Syria in breach of European Union sanctions.

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The reported Iranian position in this is confusing at the moment. Mr Hunt stated that Mr Zarif had told him the Steno Impero had been captured in “tit-for-tat” for Grace 1.

However, Tehran has also said the tanker had been detained after colliding with a fishing boat and then refusing to stop. An arrest was carried out under international law and the ship taken to the port of Bandar Abbas, according to the country’s official news agency. The issue of the Gibraltar seizure does not feature in this version.

The foreign secretary has pointed out that the UK has tried to de-escalate the situation with offers of talks to release Grace 1 and its cargo of oil in return for assurances the oil would not be taken to Syria.

Yesterday, Mr Hunt tweeted: “Having assured me last Sat[urday] Iran wanted to de-escalate the situation they have behaved in the opposite way. This has to be about actions not words if we are to find a way through. British shipping must and will be protected.”

Penny Mordaunt, the defence secretary, confirmed that a Royal Navy frigate was an hour from the scene when Iranian forces took over the Stena Impero which, she insisted, was in Omani waters at the time.

Iran releases drone footage of US warships to 'disprove' Trump claims the craft was downed

The Royal Navy currently has a frigate, with another one about to arrive, four mine-hunters and a Royal Fleet Auxiliary support ship stationed near the Gulf along with Royal Marines. But the message from London was that military action was not being contemplated.

Mr Hunt had declared there would be robust action if the British tanker was not released. But he also stressed that this did not include the use of armed forces.

He said on Saturday evening that he would make a statement to the Commons on Monday which, unless something dramatic happens in the next 24 hours, appears to suggest that the Marines are not about to storm Bandar Abbas.

The French and German foreign ministries condemned the Iranian seizure of the tanker. Emmanuel Macron’s government said such an action harmed de-escalation efforts in the region, while Angela Merkel’s office stated it was an unjustifiable intrusion on shipping through a key shipping route and urged Iran to release the ship and crew.

Donald Trump says Iran is 'Nothing but trouble'

Looming over all this is the shadow of Mr Trump. The American dispatch of troops, Patriot missiles and a squadron of F-22 warplanes to Saudi Arabia looks like yet another ratcheting up of the confrontation.

But the US president also confirmed on Friday that he had appointed senator Rand Paul to negotiate with Iran to reduce tension, contradicting, in typical Trump fashion, what he had said 24 hours earlier on the matter.

The Paul appointment is important. The senator has been a consistent advocate against American military adventures abroad, albeit from a right-wing perspective. He would be a counterweight to John Bolton, the national security advisor who, like Mr Trump, is a Vietnam draft dodger, but has been consistent advocate of US military intervention and has, in the past, spoken of his desire for regime change in Iran.

Mr Paul has also been among those in Congress who had attempted to block the sale of arms to Saudi Arabia – something which runs totally counter to Mr Trump’s position on the issue.

Iranian authorities 'seize British oil tanker in Persian Gulf'

So there are now contradictory and confusing messages from Tehran and Washington in a highly volatile situation.