A Russian spy ship is on the edge of UK waters north of Scotland and has pointed lasers to distract pilots of surveillance aircraft monitoring its activities, the defence secretary has said.

Speaking at a press conference in Downing Street, John Healey said it was the second time in a year that the Yantar had entered UK waters.

The ship is “designed for gathering intelligence and mapping our undersea cables”, Healey told journalists.

“My message to Russia and to Putin is this: we see you. We know what you’re doing. And if the Yantar travels south this week, we are ready,” he added.

Giving more details on the vessel, Healey said: “It is part of a Russian fleet designed to put and hold our undersea infrastructure and those of our allies at risk.

“It isn’t just a naval operation. It’s part of a Russian programme driven by what they call the Main Directorate of Deep-Sea Research, or GUGI, and this is designed to have capabilities which can undertake surveillance in peacetime and sabotage in conflict.

“That is why we’ve been determined, whenever the Yantar comes into British wider waters, we track it, we deter it and we say to Putin we are ready, and we do that alongside allies.”

He said this was a demonstration of Britain’s capability and “readiness to act”.

The defence secretary issued a warning in January about the ship after it was spotted in UK waters.