The British Government is expected to announce today that a public inquiry will be held into the death of poisoned ex Russian spy Alexander Litvinenko.
Mystery has surrounded the death of the former KGB officer since he died after drinking tea laced with radioactive polonium-210 with two ex colleagues at a London hotel in 2006.
But the latest move, which will be announced in a written statement by Home Secretary Theresa May, will mean investigators can probe whether the Russian state was behind his murder.
The Government has until now resisted launching a public inquiry, and instead said it would “wait and see” what a judge-led inquest found.
But Mr Litvinenko’s widow Marina challenged this and the High Court ruled the UK's Home Secretary must reconsider its decision.
The move is likely anger Russian President Vladimir Putin at a time when relations are strained in the aftermath of the downing of the Malaysia Airlines flight in Ukraine.
The Daily Telegraph said that Mrs May will tell say that a public inquiry will take over from the inquest.
Mr Litvinenko, 43, who fled to Britain in 2000, was poisoned with radioactive polonium-210 while drinking tea with two Russian men, one a former KGB officer, at the Millennium Hotel in London’s Grosvenor Square.
His family believes he was working for MI6 at the time and was killed on the orders of the Kremlin.
Former KGB bodyguard Andrei Lugovoi and Dmitri Kovtun have been identified as the prime suspects, but both deny any involvement and remain in Russia.
Ministers have been under pressure since last year when Sir Robert Owen, who was conducting the inquest, said he could not hold a “fair and fearless” investigation.