Investigators say they have evidence linking a third man to the Novichok poisonings that left one British woman dead, and another four fighting for their lives.
Denis Sergeev, who used the alias Sergey Fedotov, is facing a string of charges including trying to kill former Russian spy Sergei Skripal, his daughter Yulia.
Undercover Russian operatives Alexander Mishkin, who used the name Alexander Petrov while in the UK, and Anatoliy Chepiga, who used the alias Ruslan Boshirov, have already been charged with conspiracy to murder.
Updating MPs in the Commons, the Home Secretary vowed decisive action in combatting the threat from Russia.
“The Government will continue to respond extremely robustly to the enduring and significant threat from the Russian state,” Ms Patel said.
“We respect the people of Russia but we will do whatever it takes, everything it takes to keep our country safe.”
More to follow…