Sir Keir Starmer has announced the UK will start confiscating Russian shadow fleet vessels as he steps up attempts to put pressure on Vladimir Putin over the war in Ukraine.
The prime minister’s announcement comes in conjunction with European allies after France, Belgium and Sweden have already boarded Russian ships in recent weeks in an attempt to cut off funding for Moscow’s war.
The move means that Britain’s commandos will be able to board and halt Russia’s shadow fleet vessels as they pass through UK waters.
There is no end in sight to the war in Ukraine despite Donald Trump’s attempts to broker a peace deal with Putin, including the US easing sanctions on Russian oil.
Sir Keir said the UK would join northern European allies in intercepting the tankers, in an attempt to “go after” the sanctions-breaking ships “even harder”.
The prime minister will travel to Helsinki, Finland, on Thursday for a summit with national leaders from the Joint Expeditionary Force (JEF).
The JEF, a military coalition of 10 northern European countries led by the UK, aims to defend against Russian incursions.
It also includes Denmark, Estonia, Finland, Iceland, Latvia, Lithuania, the Netherlands, Norway and Sweden.
Moscow’s shadow fleet is reported to be made up of more than a thousand ageing tankers.
They illicitly ship oil and other goods out of Russia by flying the flags of other countries, with the aim of evading sanctions imposed by the West since the invasion of Ukraine began.
JEF countries Finland, Sweden and Estonia have recently intercepted suspected shadow tankers travelling through the Baltic.
Closing off British waters to the shadow fleet seeks to force the Russian vessels into taking longer, more costly sea routes, or risk being intercepted by the UK.
Sir Keir said: “We are living in an increasingly volatile and dangerous world, facing threats from different fronts across the world every day.
“As prime minister, my first duty is to keep this country safe and protect British interests here and abroad.
“Putin is rubbing his hands at the war in the Middle East because he thinks higher oil prices will let him line his pockets.
“That’s why we’re going after his shadow fleet even harder, not just keeping Britain safe but starving Putin’s war machine of the dirty profits that fund his barbaric campaign in Ukraine.
“He and his cronies should be in no doubt, we will always defend our sovereignty and stand with Ukraine for as long as it takes.”
British forces have already been involved in tracking shadow fleet vessels for several years, and have supported operations by other countries to seize the ships.
In January, the UK assisted in the seizure of the oil tanker Marinera by the US.
Previously known as the Bella-1, the Russian-flagged vessel was captured by American forces aided by RAF aircraft and the British supply ship RFA Tideforce in the Atlantic.
Later that same month, Royal Navy patrol boat HMS Dagger helped the French seize another sanctioned ship, the Grinch, in the western Mediterranean, shadowing the vessel through the Strait of Gibraltar.
Last week, the French intercepted the Deyna oil tanker in the Mediterranean, supported by the UK.
Libyan authorities have meanwhile towed a suspected shadow fleet oil tanker found drifting in the Mediterranean which was believed to have been hit in a drone strike.
The tanker, carrying liquefied natural gas, was towed to avoid a spill in the Mediterranean.
At the JEF summit, the prime minister and other leaders are expected to discuss shared security in the so-called High North and the war in Ukraine.
