Russia's defence ministry said on Saturday that British navy personnel blew up the Nord Stream gas pipelines last month, a claim that London said was false and designed to distract from Russian military failures in Ukraine.
Russia did not give evidence for its claim that a leading NATO member had sabotaged critical Russian infrastructure amid the worst crisis in relations between the West and Russia since the depths of the Cold War.
The Russian ministry said that "British specialists" from the same unit directed Ukrainian drone attacks on ships of Russian Black Sea fleet in Crimea earlier on Saturday that it said were largely repelled by Russian forces, with minor damage to a Russian minesweeper.
"According to available information, representatives of this unit of the British Navy took part in the planning, provision and implementation of a terrorist attack in the Baltic Sea on September 26 this year - blowing up the Nord Stream 1 and Nord Stream 2 gas pipelines," the ministry said.
Britain denied the claim.
"To detract from their disastrous handling of the illegal invasion of Ukraine, the Russian Ministry of Defence is resorting to peddling false claims of an epic scale," the British defence ministry said.
"This invented story, says more about arguments going on inside the Russian government than it does about the West."
Maria Zakharova, a spokeswoman for Russian foreign ministry, said Moscow will seek reaction from the U.N. Security Council saying on social media Moscow wanted to draw attention to "a series of terrorist attacks committed against the Russian Federation in the Black and Baltic Seas, including the involvement of Britain in them".
Russia, deeply isolated by Western nations since its Feb. 24 invasion of Ukraine, has previously blamed the West for the explosions that ruptured the Russian-built Nord Stream 1 and Nord Stream 2 pipelines on the bed of the Baltic Sea.
But it had not previously given specific details of who it thinks was responsible for the damage to the pipelines, previously the largest routes for Russian gas supplies to Europe.
A sharp drop in pressure on both pipelines was registered on Sept. 26 and seismologists detected explosions, triggering a wave of speculation about sabotage to one of Russia's most important energy corridors.
Reuters has not been able to immediately verify any of the conflicting claims about who was to blame for the damage.