Russia has dismissed a warning by Defence Secretary Gavin Wiliamson that Moscow could cause “thousands and thousands and thousands” of deaths in Britain with an attack that would cripple the UK's infrastructure and energy supply.

In an interview with the Telegraph, Gavin Williamson said Russia has been researching the UK’s critical national infrastructure and how it connects to continental power supplies with a view to creating "panic" and "chaos".

Delivering his assessment of the threat from what he calls an increasingly assertive Kremlin, he said it was willing to take action “that any other nation would see as completely unacceptable”.

However, Igor Konashenkov, a spokesman for the Russian Defence Ministry, responded on Friday by saying it is likely Mr Williamson "has lost his grasp on reason".

"The minister's fear of Russia photographing electric power plants or studying the routes of British gas pipelines is like something out of a children's comic or the show 'Monty Python's Flying Circus'," Mr Konashenkov said.

"If these statements are an attempt by Wilson to attract attention to himself, he will be far from the first defence minister to try to score political points by playing up the Russian threat to the British," Mr Konashenkov added in a written response which misnamed Mr Williamson variously and throughout.