A Russian "spy" ship reportedly stopped off at sites off the Essex coast as part of plans to sabotage key energy infrastructure, it has been claimed. 

A joint report by broadcasters in Denmark, Sweden, Finland and Norway claims the Admiral Vladimirsky was part of an operation to map undersea infrastructure.

It has been reported that the ship sailed around the Baltic and North Sea for about a month stopping at wind farms across Britain. 

The broadcasters say that the ship is part of a fleet of espionage boats, disguised as fishing trawlers and scientific research vessels, which is examining key energy sites for possible sabotage.

Danish broadcaster DR has published video of an encounter at sea between a small boat carrying their team and the Russian ship, filmed off the Danish coast in November.

It shows a man, wearing a balaclava and military gear and carrying an assault rifle, appearing on the deck of the Admiral Vladimirsky.

The ship is thought to have entered the Moray Firth, off the coast of Scotland, on November 10 last year.

Chairman of the Commons Defence Committee Tobias Ellwood told The Telegraph that the UK must expand its armed forces in response.

“We simply can no longer protect our near seas and, rightly, step forward further afield, with our current peacetime-sized Navy, Army and Air Force,” he said.

An MoD spokesman said: “The Government takes the security and resilience of our national infrastructure very seriously.

“That is why we increased Royal Navy presence patrols after the Nord Stream incident and have invested £65 million in the first of our two Multi-Role Ocean Surveillance ships.

“We continue to review all our investments and activities against the full range of threats and risks.”