Den russiske regjering var innblandet i, eller sto bak drapet på den russiske avhopperen Alexander Litvinenko i London i 2006, sier kilder i den britiske regjering til BBC.
The murder of former Russian agent Alexander Litvinenko was carried out with the backing of the Russian state, Whitehall sources have told the BBC.
A senior security official has told Newsnight there are «very strong indications it was a state action».
The BBC has been told that Russia’s internal security organisation, the FSB, operated under Mr Putin with far more autonomy than the organisations usually entrusted with foreign espionage operations.
Our source said: «We very strongly believe the Litvinenko case to have had some state involvement.»
Newsnight has also learned that officers at MI5 believe they thwarted an attempt last summer to kill another Russian dissident, Boris Berezovsky.
Mr Lugovoi claims he was also a victim of polonium poisoning
The BBC’s source said the Berezovsky incident showed «continued FSB willingness to consider operations against people in the West».
And they claimed the targeting of Russian government critics in the UK had serious diplomatic repercussions, saying: «[It] messes up the relationship big time.»