The Fontanka news website named on Wednesday a third GRU military intelligence operative, Sergey Fedotov, as having been involved in trying to kill ex-spy Sergei Skripal in the English city of Salisbury.
The website said records show Fedotov visited Britain in 2016, 2017 and 2018 and left the country on March 4 this year, the same day as two other GRU agents who have already been named.
Skripal and his daughter Yulia were found slumped on a public bench in Salisbury on that date, and the case prompted the biggest East-West diplomatic expulsions since the Cold War.
Britain said they were poisoned with Novichok, a military-grade nerve agent developed by the Soviet Union, and has accused two men it says are officers from Russia's GRU military intelligence service of carrying out the attack.
Moscow has repeatedly denied any involvement in the poisoning, as have the two men identified by Britain.
Last month, the Telegraph newspaper said British police had identified a third Russian intelligence officer they believe carried out a reconnaissance mission before the attempted murder of Skripal. The paper did not name him.