A Russian warship fired warning shots near a UK‑registered yacht in the English Channel on Tuesday.
The incident, which happened at around 11:40 am BST between the Isle of Wight and Normandy, involved a Russian frigate, the Admiral Grigorovich.
BBC News understands that the small, motor‑less yacht had drifted towards the warship in foggy conditions after setting off from the UK.
The Russian vessel fired warning shots after sounding an audible warning to get the yacht to move out of its way.
No injuries or damage to the yacht have been reported.
A Ministry of Defence spokesperson said: We are investigating reports of an incident in the Channel.
British authorities received reports from the yacht's occupants that the Russian vessel had fired warning shots from around 500 yards (457 metres) away – a relatively near distance by the standards of sea travel.
The incident happened around 20 nautical miles – around 23 standard miles south of the Isle of Wight, outside UK territorial waters.
Russian warships regularly pass through the Channel and are routinely monitored by Royal Navy vessels.
The frigate thought to be involved was being shadowed by the HMS Mersey; it was being tracked by HMS Tyne and HMS Mersey over the weekend.
Last week, a NATO source told BBC Verify that the Admiral Grigorovich had been ordered by Moscow to escort shadow fleet vessels through the Channel.
The incident is being treated as an isolated event separate from a previous operation intercepting a Russian shadow fleet tanker carrying sanctioned oil.
