The report of the official inquiry into the death of former Russian spy Alexander Litvinenko is to be published on January 21.
The inquiry said its findings will be released in Parliament 48 hours after the report is delivered to Home Secretary Theresa May.
Mr Litvinenko, an outspoken critic of Vladimir Putin, died after drinking tea laced with radioactive polonium in a London hotel in 2006.
The inquiry, chaired by Sir Robert Owen, heard claims that the Russian president personally ordered the killing.
The inquiry into Mr Litvinenko's death opened in January following a lengthy legal battle by his widow, Marina.
In February 2014, the High Court ruled that the Home Office had been wrong to rule out a public inquiry before the outcome of an inquest into his death.
Mr Litvinenko, a former FSB and KGB spy, died in hospital on November 23 2006, three weeks after having tea with two other former Russian agents at the Millennium Hotel in Grosvenor Square.
In May 2007, the Director of Public Prosecutions decided that one of the ex-agents - Andrei Lugovoi - should be charged with his murder.
Moscow, however, refused to extradite him - arguing that the Russian constitution did not allow it - while Mr Lugovoi denied any involvement in Mr Litvinenko's death.