LONDON

British forces have been authorized to board and detain ships suspected of belonging to Russia’s so-called shadow fleet transiting UK waters, the government announced Wednesday.

The decision came ahead of Prime Minister Keir Starmer’s visit to Finland on Thursday for a summit of the Joint Expeditionary Force, a UK-led military coalition of northern European nations, where he is expected to push for closer coordination in tackling the fleet.

"We will always defend our sovereignty and stand with Ukraine for as long as it takes," Starmer said.

The move is aimed at disrupting a network of tankers accused of operating without valid national flags to evade sanctions on oil exports and help fund Moscow’s war in Ukraine.

Western governments say the shadow fleet, made up of ageing tankers with opaque ownership structures, has become a key tool for Russia to continue exporting oil despite sanctions imposed over its war in Ukraine.

Meanwhile, the US has temporarily lifted sanctions on Russian oil already at sea in a bid to stabilize energy markets amid rising fuel prices linked to the war in Iran.

“We are living in an increasingly volatile and dangerous world, facing threats from different fronts across the world every day. Putin is rubbing his hands at the war in the Middle East because he thinks higher oil prices will let him line his pockets," Starmer said.

“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 added.

Earlier this year, British armed forces assisted US troops in seizing the Marinera oil tanker, which American officials accused of breaching sanctions by transporting oil linked to Venezuela, Russia and Iran.