The Royal Navy has warned of increasing Russian activity around the UK’s waters after it spent 21 days in July monitoring Moscow’s ships.

Naval operations to monitor Russian vessels increased by 25% last month compared with the previous year, with warships making repeated voyages through the strait of Dover and the North Sea.

Offshore patrol vessels HMS Tyne, HMS Mersey and HMS Severn, alongside Wildcat helicopters from 815 Naval Air Squadron and Merlin submarine-hunting aircraft, were deployed throughout the month to shadow Russian frigates Neustrashimy and Admiral Grigorovich, which are tasked with escorting so-called “shadow fleet” tankers.

Last month, the Ministry of Defence (MoD) said in its annual report that Royal Navy vessels had been “activated” 116 times in the year to March 2026, shadowing 61 Russian warships and 28 merchant vessels around the UK’s waters.

This reflected a 30% increase in Russian naval activity over the previous two years and included operations to deter the spy ship Yantar, which was spotted near undersea cables off Scotland last November.

Vladimir Putin has been accused of using the Kremlin’s shadow fleet of ageing vessels to evade international sanctions on its oil and fund the war in Ukraine.

The increase in Russian naval activity follows the seizure of the tanker Smyrtos by Royal Marines in June, the first time British troops have directly boarded a shadow fleet vessel.

The MoD said the diversion of ships from Russia to escort shadow fleet vessels meant the country was “using up valuable operational capacity to constantly guard cargo”.

The UK has already imposed sanctions on more than 500 vessels, and Russia’s oil and gas revenues fell by 24% year on year in 2025.

HMS Tyne was also tasked with monitoring the Neustrashimy as it carried out a live-firing exercise outside British and French waters on 20 July.

Another ship, the frigate HMS Somerset, has been involved in monitoring Russian activity in the North Atlantic as part of a four-month Nato deployment searching for submarines, alongside helicopters from the Navy’s Fleet Air Arm.

Somerset’s commanding officer, Cmdr Matt Millyard, said on Saturday: “This deployment demonstrates exactly what the Royal Navy exists to do: protect the UK and our allies from wherever our interests are threatened.

“I am immensely proud of every single member of the ship’s company for what we have achieved over the past four months.”