The Russian Embassy in London has condemned the move as "piracy"

Russia has slammed the UK after it threatened to interdict, board, and seize vessels in British waters that it considers to be part of the alleged Russian 'shadow fleet.'

Moscow has denied operating a shadow fleet and has condemned the seizure of vessels on the high seas, calling it "piracy." 

In a statement on Wednesday, Downing Street said London would coordinate with its allies in the Joint Expeditionary Force (JEF) - a group of ten European NATO members - to "close off UK waters, including the [English] Channel, for sanctioned vessels."

The goal is to force vessel operators to "either divert to longer, financially painful routes, or risk being detained by British forces," the statement said.

In recent weeks, British military and legal specialists have prepared scenarios for cases "including boarding vessels that don't surrender, are armed, or use high tech pervasive surveillance to evade capture," it said.

In each potential seizure, British law enforcement, military, and energy market specialists will consider a ship before making a recommendation to ministers prior to execution, Downing Street said.

The Russian Embassy in London condemned the "deeply hostile step," accusing the UK of planning to carry out "acts of piracy."

"The stated objectives - combined with the timing of this announcement - leave no room for doubt that the recent escalation of Ukrainian attacks on Russian energy infrastructure also occurred with the involvement of the British side," it said in a statement on Thursday.

Russia has long described Britain as a key force behind the Ukraine conflict, accusing it of directly participating in Ukrainian long-range strikes against Russian cities using UK-made weapons.

Ukrainian forces have increased attacks on Russian oil and gas infrastructure in recent months. Ukraine has also attacked ships it sees as linked to Russia in the Black Sea with naval drones.

On Thursday, Trkiye's Foreign Ministry reported that a Turkish-operated tanker in the country's economic zone was hit by naval drones. It did not assign blame at the time of writing.