The threat level for UK ships in Iranian waters was raised to its highest level this week — with officials claiming that the risk of an attack is “critical.”

The move was announced Tuesday by the British Ministry of Defense, the BBC reports.

It came just one day before a reported incident in the Strait of Hormuz, which saw a group of boats belonging to Iran’s Islamic Revolution Guard Corps (IRGC) allegedly attempt to stop a UK oil tanker before being scared away by a Royal Navy ship.

“The crew of HMS Montrose yesterday ensured the safe passage of the merchant vessel British Heritage through the Strait of Hormuz,” said Defense Secretary Penny Mordaunt in a statement Thursday. “I would like to thank the Royal Navy for their professionalism, which upheld international law and supported freedom of navigation through a shipping channel that is vital to global trade.”

Mordaunt called out Iran for the incident, saying: “The UK government is concerned by this action and we urge Iranian authorities to de-escalate the situation.”

The rise in threat level ultimately means British tankers are now advised to stay out of Iranian waters, according to the BBC.

Wednesday’s incident in the Strait of Hormuz unfolded nearly a week after British Royal Marines boarded and seized an Iranian tanker off Gibraltar — under the belief that it was violating European Union sanctions by shipping oil to Syria.

​Iranian President Hassan Rouhani issued a stern warning to the UK on Wednesday, saying the country would face “consequences” for seizing its vessel. ​

IRGC officials have ​denied any involvement​ with the latest confrontation.

The back-and-forth comes amid heightened tensions between the US and Iran — with ​President Trump going so far as to order a military strike against the Middle Eastern nation last month, which he called off, after it downed an unmanned US surveillance drone​.

“They shot down an unmanned drone flying in International Waters,” Trump tweeted afterward. “We were cocked & loaded to retaliate last night on 3 different sights (sic) when I asked, how many will die…150 people, sir, was the answer from a General. 10 minutes before the strike I stopped it, not proportionate to shooting down an unmanned drone.”

Trump went on to say that he was “in no hurry” to start a war with the Iranians.

“Our Military is rebuilt, new, and ready to go,” he said. “By far the best in the world.”

Washington has boosted its military presence in the Persian Gulf in recent months — sending the USS Abraham Lincoln aircraft carrier strike group, jet fighters, B-52 bombers and Patriot anti-missile batteries to Qatar.

Iran has been under fire for exceeding the caps on enriched uranium that were set by the 2015 nuclear accord and has been asking European powers to provide sanction relief. Trump chose to withdraw the US from the deal last year and instead reimposed economic penalties against Tehran. The countries that remain are Britain, France, Germany, the European Union, Russia and China.

With Post wires