The foreign secretary Jeremy Hunt made a statement to the Commons on Monday outlining the tough measures the UK was proposing to take to persuade Iran to release the British-flagged tanker, the Stena Impero, and its 23-strong crew.

Eighteen of them, including the captain, who has been named as Vinay Singh, are Indian.

Britain is to seek to put together a European-led maritime mission to protect ships sailing through the Strait of Hormuz, he said. Hunt described the seizure by Iran of a British-flagged tanker on Friday as an act of “state piracy”.

“We will seek to put together a European-led maritime protection mission to support safe passage of crew and cargo in this vital region,” he revealed.

“We have had constructive discussion with a number of countries in the last 48 hours and we will discuss later this week the best way to complement this with recent US proposals in this area.”

Hunt told MPs: “It is with a heavy heart that we are announcing this increased international presence in the Gulf because the focus of our diplomacy has been on de-escalating tensions in the hope that such changes would not be necessary.

“If Iran continues on this dangerous path, they must accept the price will be a larger western military presence in the waters along their coastline, not because we wish to increase tensions but simply because freedom of navigation is a principle which Britain and its allies will always defend.”

Hunt, replying to a question from Labour, said the UK has sought to de-escalate the situation but there “will be no compromise” on freedom of navigation in the Strait of Hormuz.

He said: “This is absolutely essential for the global economy and for global freedom of navigation. This country will not blink in that respect.”

The UK apparently wants to include India, along with Russia and China, in trying to find a multilateral approach to finding a diplomatic solution.

Defence minister Tobias Ellwood, speaking on ITV’s Good Morning Britain, said: “So, this is something that affects us all, it requires international co-operation.”

However, Russia waded in to take the side of its ally — Iran — accusing Britain of “'piracy” for seizing the Iranian Grace 1 tanker off Gibraltar on July 4.

US secretary of state Mike Pompeo told Fox News: “The responsibility ... falls to the United Kingdom to take care of their ships.”

Meanwhile, Tehran released video footage of some of the crew sitting around a table speaking with one of their captors, which some in London interpreted as a taunt to Britain.

The video shows seven of the crew wearing red jumpsuits and sitting around a table, as one Iranian guard can be heard thanking them for their cooperation. The cameraman can also be heard telling them not to look at him.

The Union Jack on the tanker has been replaced with the Iranian flag.

Pictures released by the semi-official Fars news agency show some of the crew — which also includes three Russians a Latvian and a Filipino — huddled cross-legged on the floor.

Standing over them is a Revolutionary Guards, while items of bedding and towels are scattered around the room.

Shoes have been taken off and piled in a corner.

More video released by Iran also shows the crew laughing while standing around a coffee machine, and the ship’s cooks preparing food in an apparent attempt to indicate they are being treated well.

The BBC’s security correspondent, Frank Gardner, said he was confident that the crew would be well treated.

He added that Britain and United States “were not on the same page” over Iran.

This is because the UK still had hopes of rescuing the Iran nuclear deal which President Donald Trump has unilaterally scrapped. This is why Britain did not want to be seen to be too close to the US.

However, others have pointed out that Britain’s only hope of providing security to its shipping in the Gulf would be to join forces with the Americans.

Earlier on Monday, in one of her last acts as Prime Minister, Theresa May chaired a meeting of the government’s emergency committee, known as COBRA, to assess the latest intelligence about the seized tanker and discuss the next course of action.

At the meeting were not only senior members of the cabinet but also the chief of the defence staff, General Sir Nick Carter.

Officials said the meeting considered options for “strengthening current reassurances” to commercial shipping as well as the response to Tehran.

The Prime Minister’s official spokesman commented: “We do not seek confrontation with Iran but it is unacceptable and highly escalatory to seize a ship going about legitimate business through internationally recognised shipping lanes.”

The spokesman said the ship was seized under “false and illegal pretences and the Iranians should release it and its crew immediately”.

Military experts have warned that cuts to the Royal Navy had left it over-stretched, with too few warships to protect British interests.

The spokesman added: “The high volume of ships moving through the Strait of Hormuz – up to 30 ships covering more than 100 nautical miles – makes it impossible to escort vessels individually.

“We already work closely with international partners to ensure a co-ordinated effort to defend freedom of navigation, this includes sharing information on threats to shipping and offering mutual protection for each other's vessels.”

Downing Street said there had not been a US offer to escort all UK ships in the region, as some MPs have claimed.

But the spokesman acknowledged: “The US has been discussing with a number of countries, including the UK, how we might deliver maritime security in the face of recent threats to shipping.”