A Russian frigate carried out a live-fire artillery exercise 46 miles (74km) south of Plymouth on Monday while being shadowed by a Royal Navy vessel. The Royal Navy monitored the exercise and is continuing to "track the vessel's activity closely", a Ministry of Defence (MoD) spokesperson said.
The Russian frigate, Neustrashimy (English: Dauntless), was also monitored by a French military aircraft which made radio contact with the warship asking it to clarify its intentions, the BBC has been told. The live-fire exercise took place in international waters and lasted for 30 minutes.
The BBC was told that, prior to opening fire, the Russian warship had informed the Royal Navy Offshore Patrol Vessel, HMS Tyne, of its intention to conduct gunnery activity. The Russian warship requested that HMS Tyne reposition to a safer distance, which it did.
The incident will be a reminder for the new prime minister of increased Russian naval activity near UK waters in recent months. UK defence sources would not comment on whether the incident might have been timed to coincide with the start of Andy Burnham's premiership.
Last month, Royal Marine Commandos boarded a Russian "shadow fleet" oil tanker in the English Channel in a six-hour operation which was the first of its kind by UK armed forces.
In June, a British couple in international waters in the English Channel came across a Russian warship - Admiral Grigorovich - 23 miles off the Isle of Wight. The frigate fired warning shots as Jane and Alan Kelvey sailed their yacht on what Russia's defence ministry said had been a "dangerous approach". However, the couple said they had not been on a "collision course".
Russian warships regularly pass through international waters in the Channel, which are separate from UK and French territorial waters.
How was the Russian warship tracked?
BBC Verify has analysed flight and ship-tracking data which shows the position of HMS Tyne and several British military aircraft operating in and around the Channel near Plymouth on Monday.
Flight data on ADS-B Exchange indicates at least four Royal Air Force and Royal Navy aircraft were flying off the coast of Dorset mostly above the UK's territorial waters, including two Eurofighter Typhoons, a Voyager air refuelling tanker and a Super Lynx helicopter.
A French military H160M Guépard helicopter also flew out and over the Channel during the afternoon. It is not clear if this is the aircraft which made contact with the Russian warship.
Data on ship-tracking service MarineTraffic shows HMS Tyne began to broadcast its location about 40 miles off Plymouth at 13:57 BST on Monday. It remained in that location for around two hours before departing at 15:56 to return to Plymouth.
HMS Tyne has been tracking Neustrashimy since at least 16 July when both vessels were also captured in the North Sea about 36 miles miles from the port of Felixstowe in Suffolk on a satellite image.
Additional reporting by Ella Kipling, Barbara Metzler, Thomas Spencer and Patrick Jackson
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