John Healey revealed that a Russian Akula-class attack submarine and two specialist submarines from Russia’s main directorate for deep sea research (GUGI) were directed by President Vladimir Putin to “conduct hybrid warfare activities against the UK and our allies, specifically around critical undersea infrastructure”.

He said they were detected within the UK’s exclusive economic zone, which stretches around 230 miles offshore.

The attack submarine was a “likely decoy” to divert attention away from the other two, he added.

A Royal Navy frigate, HMS St Albans, was used in the operation along with RFA Tidespring. Merlin helicopters and RAF Boeing “submarine hunting” aircraft also tracked the Russian vessels.

The operation involved working with the Norwegian military.

Moscow has rejected claims that the ships pose a threat to the UK’s critical underwater infrastructure, Russian news agency TASS reported.

Mr Healey said: “I’m making this statement to call out this Russian activity.  To President Putin, I say – we see you, we see your activity over our cables and our pipelines, and you should know that any attempt to damage them will not be tolerated and will have serious consequences.”

He then said the UK’s undersea network was highly resilient but that the number of threats to it are increasing, adding: “Putin’s covert operation failed because this government is delivering our first duty – protecting Britain.”

The operation used more than 500 British personnel and has now ended, he added.

He also said there was “no evidence” that the Russian submarines had caused any damage to UK underwater cables or pipelines.

Distracted by the Middle East

But he claimed it was “pretty clear” that Putin wants the UK to be distracted by the war in the Middle East, in response to a question from Sky News’ security and defence editor, Deborah Haynes.

“What I’m setting out today demonstrates that we are not just exposing his covert operation, but we are saying to him that we recognise Russia as the primary threat to the UK and to NATO, and that we will not take our eyes off Putin, whilst at the same time we act to protect our British interests and our British allies in the Middle East.”

Defence spending

Asked by Ms Haynes if he believes the UK’s defence spending needs to be pushed towards 3% faster, he said: “I would just say to you, look back at the speeches that the chancellor has made. She has quite rightly argued that a strong economy needs strong national security.