A third Russian faces charges over his alleged involvement in the 2018 Salisbury poisonings, which left three people critically ill and one dead.
Security sources believe Denis Sergeev was the on-the-ground commander in the Novichok attack on former double agent Sergei Skripal and his daughter Yulia.
Dawn Sturgess died after the poisoning and a police officer was badly injured.
Prime Minister Boris Johnson said that "the suspects should be handed over for justice".
Russian Foreign Ministry spokeswoman Maria Zakharova said the UK was using the case as "a tool to put pressure on our country", adding: "We decisively reject all of London's attempt to blame Moscow for what happened in Salisbury."
Police confirmed they believe the suspects in the case belonged to a team from the GRU, Russia's military intelligence service.