Litvinenko suspect to 'throw doubt' over involvement in killing
A key suspect in the killing of ex-Russian spy Alexander Litvinenko will disprove allegations he was involved in the poisoning, he has told the BBC.
The UK public inquiry is on hold after a last-minute offer by Dmitry Kovtun to give evidence via video link.
He, along with Andrei Lugovoi, is accused of poisoning Mr Litvinenko, who died in London on 23 November 2006.
Mr Kovtun, who was named as a suspect in 2007, said he had "material" which would throw doubt on the case.
Mr Litvinenko is believed to have been given a fatal dose of polonium-210 in his tea during a meeting in a London hotel.
He was an officer with the Federal Security Service - the successor to the KGB - but fled to Britain where he became a UK citizen and fierce Kremlin critic.
Inquiry chairman Sir Robert Owen and senior lawyers have expressed concern about what lies behind Mr Kovtun's last-minute decision to testify.
Until now neither suspect has given evidence to the inquiry.
Lawyers were due to make closing statements but that has been postponed to allow Mr Kovtun - a former Russian military officer - to give evidence via videolink from Moscow.
If he came to Britain, he would be arrested and officially charged with murder.
He told the BBC he had "heard a lot of statements which are easy to refute" and by participating could "get access to the documents - including the secret material - so I can make my own conclusions".
The Litvinenko case
- 23 Nov 2006 - Mr Litvinenko dies three weeks after having tea with former agents Andrei Lugovoi and Dmitri Kovtun in London
- 24 Nov 2006 - His death is attributed to polonium-210
- 22 May 2007 - Britain's director of public prosecutions decides Mr Lugovoi should be charged with the murder of Mr Litvinenko
- 31 May 2007 - Mr Lugovoi denies any involvement in his death but says Mr Litvinenko was a British spy
- 5 Jul 2007 - Russia officially refuses to extradite Mr Lugovoi, saying its constitution does not allow it
- May-June 2013 - Inquest into Mr Litvinenko's death delayed as coroner decides a public inquiry would be preferable, as it would be able to hear some evidence in secret
- July 2013 - Ministers rule out public inquiry
- Jan 2014 - Marina Litvinenko in High Court fight to force a public inquiry
- 11 Feb 2014 - High Court says the Home Office had been wrong to rule out an inquiry before the outcome of an inquest
- July 2014 - Public inquiry announced by Home Office