Defence Secretary Gavin Williamson made the unusually alarmist comments in an interview with the Daily Telegraph, in which he also said Russia was spying on the UK's critical infrastructure.

"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'," said Russian defence ministry spokesman Igor Konashenkov.

The location of electric power plants and pipelines were as secret as "Westminster Abbey or Big Ben," the spokesman 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," Konashenkov added in a written response which misnamed Williamson variously and throughout.

The strongly worded statement suggested Britain's military staff be "recertified" by the medical board if they were giving Williamson such information.

The interview was more likely an attempt to boost the defence ministry's budget, Konashenkov added.

Russian President Vladimir Putin's spokesman Dmitry Peskov had earlier declined to comment.

Williamson, who only became defence chief in November after his predecessor Michael Fallon resigned over allegations of misconduct, gave the interview at the outset of a new five-month defence review.

According to British reports, he is pressuring finance minister Philip Hammond to allocate more money to defence and scrap further cuts to Britain's strained armed forces.