Britain has denied Russian claims that Royal Navy personnel blew up the Nord Stream gas pipelines last month, saying the story is "invented".
A Ministry of Defence tweet said: "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.
"This invented story says more about arguments going on inside the Russian government than it does about the West."
The 760-mile pipelines run from Russia to Germany, via the Baltic Sea, at a depth as low as 110 metres.
They were the most important supply route for Russian gas supplies to Europe, with a joint annual capacity of 110 billion cubic metres - more than half of Russia's normal gas export volume.
But Russia cut off supply via Nord Stream 1 at the end of August, and Nord Stream 2 never entered service, as Germany paused its certification process shortly before Russia invaded Ukraine in February.
On 26 September, the pipelines registered a sharp drop in pressure and seismologists detected explosions before four leaks were recorded.
Russia said on Saturday: "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 26 September this year - blowing up the Nord Stream 1 and Nord Stream 2 gas pipelines."
It did not share any evidence to back up its claims.
Russia was initially blamed for sabotaging the pipelines as part of its efforts to deprive Europe of energy, but it dismissed these claims as "stupid", instead blaming the US.
The US destroyed the pipelines, so it could sell more liquefied natural gas to Europe, Russia said - a claim denied by the US.
Sweden and Denmark concluded the leaks were caused by explosions, but did not say who might be responsible.
Swedish prosecutor Mats Ljungqvist called on Friday for a "supplementary crime scene investigation" at the site, adding: "It is important both for the preliminary investigation and for the various collaborations we have that we now get to work in peace and quiet."
Meanwhile, Russia has also claimed "British specialists" directed Ukrainian drone strikes on ships in the Black Sea Fleet in the Crimean city of Sevastopol early on Saturday.
Russia's defence ministry said: "Nine unmanned aerial vehicles and seven autonomous marine drones were involved in the attack.
"The preparation of this terrorist act and the training of servicemen of the Ukrainian 73rd Special Center for Naval Operations were carried out under the guidance of British specialists located in the town of Ochakiv."