Donald Trump has said the UK should send warships to help keep the strait of Hormuz open.

In a post on his Truth Social platform, the US president urged the UK and other countries to deploy vessels to the strait amid the conflict with Iran.

The strait is a key trading artery between the Persian Gulf and the Gulf of Oman, through which a fifth of the world’s oil passes. Last year, about 20m barrels of oil passed through the strait each day.

Since the US and Israel first launched strikes on Iran a fortnight ago, numerous ships travelling through the strait have been attacked. It is now effectively closed, driving up oil prices and putting intense pressure on the global economy.

Trump wrote on Saturday: “Many Countries, especially those who are affected by Iran’s attempted closure of the Hormuz Strait, will be sending War Ships, in conjunction with the United States of America, to keep the Strait open and safe.

“We have already destroyed 100% of Iran’s Military capability, but it’s easy for them to send a drone or two, drop a mine, or deliver a close range missile somewhere along, or in, this Waterway, no matter how badly defeated they are.

“Hopefully China, France, Japan, South Korea, the UK, and others, that are affected by this artificial constraint, will send Ships to the area so that the Hormuz Strait will no longer be a threat by a Nation that has been totally decapitated.

“In the meantime, the United States will be bombing the hell out of the shoreline, and continually shooting Iranian Boats and Ships out of the water. One way or the other, we will soon get the Hormuz Strait OPEN, SAFE, and FREE!”

In response to Trump’s post, Iran said that claims its military capabilities had been destroyed were based on “fabricated lies”.

An Ministry of Defence spokesperson said: “As we’ve said previously, we are currently discussing with our allies and partners a range of options to ensure the security of shipping in the region.”

R Adm Neil Morisetti, who navigated and captained British warships in the region in the 1980s and 1990s, believes the risks are now “too great” to guarantee the safety of oil tankers in the strait of Hormuz.

His warning comes after the UK sent HMS Dragon, which left for the Mediterranean on Tuesday.

Morisetti, in charge of military escorts during the Iran-Iraq war, told the Sunday Times: “I think that’s why you’re hearing people saying we hope to escort the tankers shortly, because it’s probably too high a threat at the moment and the risks are too great.”

Trump’s plea to the UK contrasts with comments made on the same social media site last week, when he accused prime minister Keir Starmer of attempting to join the conflict after he had already claimed victory.

“The United Kingdom, our once Great Ally, maybe the Greatest of them all, is finally giving serious thought to sending two aircraft carriers to the Middle East,” Trump wrote. “That’s OK, Prime Minister Starmer, we don’t need them any longer – But we will remember. We don’t need people that join Wars after we’ve already won!”

The UK did not join the initial strikes on Iran, which killed its supreme leader Ayatollah Ali Khamenei. Starmer has defended his decision not to get directly involved in the military campaign.

This week, he told MPs: “President Trump has expressed his disagreement with our decision not to get involved in the initial strikes, but it is my duty to judge what is in Britain’s national interest.”