The UK has been warned that its actions would “not go unpunished” should it intercept Russian vessels. The Foreign Secretary, Yvette Cooper, said last week that Britain is ready to work with its European allies in order to intercept boats from Vladimir Putin’s so-called “shadow fleet”, which is used to transport sanctioned goods, particularly oil.

Now, the Russian Ambassador to the UK, Andrey Kelin, has told Izvestia that this would effectively mean a return to the age of piracy. He said: “What politicians in London are talking about is essentially a return to the era of the pirate Edward Teach, known as Blackbeard. What they forget is that Britain has long ceased to be the ‘ruler of the seas,’ and its actions will not go unpunished.”

Ms Cooper has not ruled out the prospect of British forces boarding seized vessels. “It means looking at whatever is appropriate, depending on the circumstances that we face,” she told Politico.

Should an incident occur during which a crew member of a ship or any British armed forces come to harm, a wider conflict could be sparked.

The Foreign Secretary also insisted that NATO should “double down” on Arctic security to defend it from Russian aggression.

“The Arctic is the gateway for Russia‘s Northern Fleet to be able to threaten the United Kingdom, to threaten Western Europe and Norway, to threaten the United States and Canada,” she said.

“So it’s a whole transatlantic security depends on our Arctic security.”

It comes as tensions continue over Donald Trump‘s want acquire Greenland for the United States from Denmark.

Sir Keir Starmer yesterday told the US President it is “wrong” to apply tariffs to the UK and other European allies opposing his efforts.

Mr Trump wrote on his Truth Social social media site: “NATO has been telling Denmark, for 20 years, that ‘you have to get the Russian threat away from Greenland’.

“Unfortunately, Denmark has been unable to do anything about it. Now it is time, and it will be done!!!”

Ms Cooper said last week: “We’ve been very clear that the future of Greenland is for the Greenlanders and for the Danes.

“Where I think there is shared agreement is about this Arctic security, this broader threat, and the need, really, for all of our countries to come together as part of that NATO alliance.”

Sir Keir’s foreign office chief added that “this is how we deal with Russian threat, which affects us all.”