LONDON — One of two Russians who Britain blames for the poisoning of former spy Sergei Skripal was named by an investigative website on Monday as a military doctor for Russia's GRU intelligence service.

Bellingcat, which covers intelligence matters, named the man as Alexander Yevgenyevich Mishkin, aged 39. He was charged by Britain last month under the name of Alexander Petrov, though prosecutors said at the time that they believed the suspects had used aliases to enter Britain.

British prosecutors charged Petrov and another man they named as Ruslan Boshirov in absentia with attempted murder for the Novichok nerve agent attack on the Skripals in the English city of Salisbury in March.

Britain's Daily Telegraph newspaper also named Mishkin in a separate report published on Monday.

Alexander Petrov, who is wanted by British police in connection with the poisoning of former Russian spy Sergei Skripal and his daughter Yulia in March. Metropolitan Police Service / AFP - Getty Images file

Bellingcat last month identified Boshirov as a colonel in the GRU whose real name was Anatoliy Chepiga.

British Prime Minister Theresa May said the attack was likely ordered at the highest levels of the Russia government, an allegation rejected by Russian President Vladimir Putin.

The Russian Embassy in the U.K. called the Bellingcat report "a display of freedom of public debate."

Bellingcat’s “investigations” are a display of freedom of public debate. Russia is ready to discuss any issues with UK authorities on the basis of official requests, not private publications. https://t.co/XQ4uXS7Xu4 pic.twitter.com/2R2NpB57mA — Russian Embassy, UK (@RussianEmbassy) October 9, 2018

The two men appeared on Russian TV in September to deny any role in the poisoning. They said they were tourists who had flown to London for fun and visited Salisbury to see its cathedral. Security analysts and others dismissed their explanation as absurd.

British police said they would not comment on speculation about the real identities of the two men facing charges, in response to a query about the latest report.

Skripal is a former colonel in Russian military intelligence who betrayed dozens of agents to Britain's MI6 foreign spy service. He and his daughter Yulia were found slumped on a public bench in Salisbury, and the British authorities said they were sickened by a Soviet-made nerve agent.

The two survived after a lengthy hospital stay in intensive care. But the nerve agent killed a British woman, Dawn Sturgess, and seriously sickened her partner.

Alexander Petrov and Ruslan Boshirov at a Salisbury train station. Metropolitan Police Service / AFP - Getty Images

The case prompted the biggest East-West diplomatic expulsions since the Cold War.

According to Bellingcat, Mishkin was born in July 1979 in the village of Loyga in northern Russia. He trained as a military doctor for the Russian naval armed forces, and was recruited by the GRU during his medical studies.

Until September 2014 his registered home address in Moscow was the same as the headquarters of the GRU.

"Bellingcat's identification process included multiple open sources, testimony from people familiar with the person, as well as copies of personally identifying documents, including a scanned copy of his passport," the website said.

Mishkin's GRU rank was unknown, it added, but based on his 15-year service was likely to be lieutenant colonel or colonel.

He was recruited by the GRU, and between 2010 and 2018 he traveled repeatedly under the identity of Alexander Petrov, including multiple visits to the Ukraine.

Last week, the Justice Department filed criminal charges against seven members of the GRU, accusing them of hacking into the U.S. Anti-Doping Agency in Colorado Springs, Colorado, as well as four international sports governing bodies.