One of the men accused of murdering poisoned Russian spy Alexander Litvinenko has said he believes the former KGB officer might have killed himself accidentally after handling radioactive material.
Dimitri Kovtun told a press conference in Moscow that he thought the death of Mr Litvinenko was an "accident" and "suicide by negligence", the Russian news agency Interfax reported.
Kovtun and Andrei Lugovoi are suspected of murdering the 43-year-old former spy, who died nearly three weeks after consuming tea laced with polonium-210 in London in November 2006.
According to Interfax, which hosted the press conference, Kovtun said: "I am more than sure that he dealt with polonium, without knowing it.
"Maybe it was leaking and polonium accumulated in his body gradually. It is possible that something he carried with him led to a gradual accumulation of polonium in the body."
On his deathbed, Mr Litvinenko accused Russian president Vladimir Putin of ordering his assassination - which the Kremlin denies.
Kovtun and Lugovoi also deny any involvement and remain in Russia, having initially refused to take part in the inquiry into Mr Litvinenko's death, which is sitting at the Royal Courts of Justice in London.
However, last month Kovtun dramatically changed his mind and offered to give evidence via video link.
The inquiry's chairman Sir Robert Owen has since said he would grant Kovtun "core participation status" and allow him to give evidence if he meets a number of conditions, including that he provides a full witness statement and discloses any relevant material.
Sir Robert said Kovtun would not be granted access to restricted confidential material despite his core participation status, putting him in the same position as Mr Litvinenko's widow and the Metropolitan Police.
Kovtun told reporters in Moscow today he would like to use this status to ask the judge to consider the evidence he believes proves his innocence.
The inquiry has been adjourned until the next provisional hearing on July 27.
The mood in Moscow was grim, a quiet rage running through the crowd. What had been planned as an opposition march against Vladimir Putin became something more, a massed protest against the bloody silencing of another voice of dissent.
Murdered Russian spy Alexander Litvinenko was warned by former security service friends as early as 2002 that he had been “sentenced to extrajudicial elimination” and should “get his will ready”, the inquiry into his death heard.