A British warship and aircraft tracked and monitored Russian submarines trying to survey vital undersea infrastructure in the North Atlantic, ensuring they fled the area, the defence secretary, John Healey, has said.

Speaking at a Downing Street press conference, Healey said the UK operation lasted more than a month and saw a Royal Navy warship and P8 marine patrol aircraft “track and deter any malign activity” by three Russian submarines.

Declining to reveal precisely where the operation took place, Healey said it did not happen in UK territorial waters but in the exclusive economic zone that extends up to 200 nautical miles from the UK coastline, or where it meets the boundary of other nations’ zones.

The submarines were a Russian Akula class nuclear-powered vessel and two deep-sea submarines from Russia’s directorate for deep sea research (Gugi), he added.

The Russian action took place “while the eyes of many were trained on the Middle East”, because of the US-Israeli attack on Iran, Healey said.

He added: “I’m making this statement to call out this Russian activity, and 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’.”

Healey said there was no evidence pipelines or cables had been damaged, but that with allies, UK forces would seek to verify this.

Describing the operation, Healey said: “A Royal Navy warship and Royal Air Force P-8 aircraft alongside allies ensured that the Russian submarines were monitored 24/7.

“The Akula submarine subsequently retreated home, having been closely tracked throughout and we continued to monitor the two Gugi submarines in and around wider UK waters.

“Our armed forces left them in no doubt that they were being monitored, that their movements were not covert, as President Putin planned, and that their attempted secret operation had been exposed. Those Gugi submarines have now left UK waters and headed back north.”

The operation involved 500 UK personnel, he added.

Asked for specifics about how the submarines were tracked and deterred, Healey said sonar buoys were dropped regularly “to demonstrate to them that we were monitoring every hour of their operation”.

He added: “And because we were watching them, we wanted to ensure that we could warn them that their covert operation had been exposed and reduce the risk that they made to attempt any action that could damage our pipelines or our cables.”

The Russian operation, Healey explained, demonstrated why the government saw Moscow “as the primary threat to the UK and to Nato”, adding: “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.”

The Ministry of Defence says Gugi had specialist surface ships and submarines that were used to survey underwater infrastructure during peacetime, but also had the capability to damage or destroy those vital links during a conflict.

The UK and its Nato allies have become increasingly concerned about the risk Moscow poses to underwater cables and pipelines, amid heightened tensions after the invasion of Ukraine.

While saying there was a need for increased defence spending, Healey said the operation showed that the UK was capable of deterring Russia.

“I think the nature of the operation that I’ve set out today demonstrates that we have UK armed forces capable of detecting, capable of deterring, capable of responding if required in order to protect Britain, protect our vital undersea infrastructure,” he added.

Asked about Donald Trump’s disparaging remarks about the contribution to Nato of European countries, Healey said: “I’m not going to comment on social media posts. What I can reflect on is the conversations that I’ve had with his secretary of war, Pete Hegseth, both one to one, and when I sit next to him at Nato defence minister meetings.

“He is clear about the US, that they remain totally, totally committed to Nato and to article 5, but equally strong in requiring European Nato nations, like the UK to step up.”

Similarly, asked if the US president’s decision to attack Iran had made Putin’s job easier by sowing confusion, Healey dodged the question.