A Russian warship disguised itself using a fake ID signal while travelling through the English Channel with two sanctioned oil tankers, a BBC Verify investigation has found.

The Boikiy – a corvette armed with guided missiles – broadcast the fake ID code as it passed through the Channel on Saturday.

On tracking sites it wrongly appeared as ships which have previously used that ID. BBC Verify matched the ID to the Boikiy by using satellite imagery, tracking data and a video of it passing under a bridge in Denmark.

It travelled alongside two vessels known to be part of Russia’s “shadow fleet” – a network of tankers whose ownership can be obscured and are used to transport sanctioned oil products.

BBC Verify has approached the Russian embassy in London for comment. But experts told BBC Verify that recent Western moves against the shadow fleet may have prompted Moscow to use its military to protect the tankers.

Last month, a Russian Su-35 fighter jet flew past a shadow fleet vessel and entered Estonian airspace after the country attempted to intercept the ship, which was suspected of carrying sanctioned oil.

“The action seems designed to deter the UK and other Nato states from attempting to board and, or, seize these vessels, since the presence of a military escort heightens the risk of confrontation and further escalation,” Dmitry Gorenburg, a senior research scientist at the Center for Naval Analyses, said.

Attention was first drawn to the Boikiy on social media by independent open-source intelligence analyst Christian Panton on Bluesky.

The ship is known to have left West Africa in June, where it was taking part in a diplomatic mission. Photos posted online showed the ship docked in Guinea’s capital, Conakry.

The corvette left port without activating its Automatic Identification System (AIS). All ships are expected to broadcast the signal, though military vessels often sail without it.

However, a vessel travelling under the generic identification number 400000000 – a code sometimes used by vessels who want to alert others to their presence for safety reasons without identifying themselves – was seen briefly near the Canary Islands.

The location is consistent with the time it could have taken the Boikiy to travel the 200km from Conakry. Satellite imagery reviewed by BBC Verify showed a 100m-long ship, matching the dimensions of the Boikiy and distinguishing it from other vessels which had used the ID.

Frederik Van Lokeren – an analyst and ex-lieutenant in the Belgian navy – noted that the Boikiy’s actions were unusual for a Russian naval vessel.

“Normally, if the Russians want to remain hidden in secret, they just turn off their AIS signal,” he said. “So for them to be camouflaging as something else… it’s very, very uncommon.”

The Boikiy was later joined by two oil tankers which had made their way from India through the Suez Canal and across the Mediterranean – the Sierra and the Naxos. Both ships have been sanctioned by the UK.

The three vessels all met at the mouth of the Channel on 20 June. Here, the Russian naval vessel appeared again in radar-based and optical satellite images, allowing us to confirm once again that it was a size and shape which matched the Boikiy.

The Naxos had reached the entrance to the Channel several days earlier than the other ships, and waited for the warship before proceeding into the channel.

A UK defence ministry source confirmed to BBC Verify that the Royal Navy shadowed the Boikiy as it passed through the Channel.

Satellite images reviewed by BBC Verify appeared to show a ship tailing the Boikiy as it transited through the waterway, but we cannot confirm that this is the Royal Navy ship.

All three vessels proceeded towards the Baltic Sea, where the Boikiy – still travelling under the fake AIS marker – was recorded passing underneath the Great Belt Bridge in Denmark.

Webcam footage showed the vessel clearly for the first time as a naval vessel.

Its unclear where the vessels are bound for, though all three have continued sailing through the Baltic and may be moving towards ports in mainland Russia or Kaliningrad – an exclave between Poland and Lithuania.