British forces are to be given permission to board sanctioned ships sailing through UK waters.
Armed forces and law enforcement officers will be able to board Russian shadow fleet vessels as part of efforts to put more pressure on Vladimir Putin as the war in Ukraine enters its fifth year.
The Royal Navy has supported allies with tracking shadow fleet ships in European and Mediterranean waters in recent weeks.
Read more: Putin's shadow fleet in the Channel
Sir Keir Starmer said: "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," he added.
PM attending military summit
It comes as the prime minister is visiting Finland for a Joint Expeditionary Force (JEF) summit in Helsinki, where he will declare the UK's support for Ukraine remains "steadfast".
The JEF is a military coalition of 10 northern European countries led by the UK and aims to prevent incursions from Russian forces.
Finland, Sweden, and Estonia have all recently carried out operations against suspected illegal shadow fleet vessels in the Baltic, while the UK provided assistance to US forces who boarded the sanctioned Russian-linked Bella 1 oil tanker in the Atlantic in January.
You can follow live coverage of the PM's trip to Helsinki in the Politics Hub - including an exclusive interview with our political editor Beth Rigby.
(c) Sky News 2026: British forces cleared to board Russian 'shadow fleet' ships in UK waters
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