The man who identified as Alexander Petrov was one of two men suspected by UK police of poisoning former GRU officer Sergei Skripal (Picture: Tass/PA).
A military doctor employed by Russia's GRU intelligence agency was one of the two Salisbury attack suspects, an investigatory website has claimed.
The two suspects in the attempted assassination of ex-Russian spy Sergei Skripal were originally named by British authorities as Ruslan Boshirov and Alexander Petrov - although it was made clear that the names were aliases.
The Bellingcat website claims the suspect identified as Petrov is, in fact, Dr Alexander Yevgenyevich Mishkin.
It claims the 39-year-old graduated from one of Russia's elite Military Medical Academies.
The website said it had identified him using a scanned copy of his passport and from the testimonies of people who knew him.
It is understood the reported identity is not disputed by British security services.
During his studies, Mishkin was allegedly recruited by the GRU military intelligence agency and by 2010 had relocated to Moscow, where he received his undercover identity - including a second national ID and travel passport - under the alias Alexander Petrov.
Bellingcat has already identified Boshirov as Colonel Anatoliy Chepiga - a highly-decorated officer in the GRU.
A spokesman for the Home Office said:
"We are not commenting as this is still a police investigation."
Around 100 UK military personnel are currently helping with the general decontamination of Salisbury following the poisoning of former Russian double spy Mr Skripal and his daughter Yulia. Both have since recovered.
Extra British personnel were deployed to begin decontamination work on Sergei Skripal's home in the city last month.
Dawn Sturgess, 44, who was later exposed to the same nerve agent, died in July.
The website says it will reveal more details of how they unmasked Mishkin later today.