One of two ex-KGB agents suspected of using a radioactive poison to kill a former spy in London has said the victim may have accidentally poisoned himself.

Alexander Litvinenko died three weeks after after meeting the two agents at a London hotel on November 1st 2006.

Speaking at a Moscow news conference, Dmitri Kovtun said Mr Litvinenko may have already been contaminated before another meeting they had in October that year.

He suggested the former spy had accidentally poisoned himself, calling it a "suicide by accident".

"I am sure he was dealing with polonium without realising," Mr Kovtun said.

"Maybe at some point there was a leak of this polonium and it was gradually storing in his body. There were outbreaks, like on October 16th when he was vomiting."

Reporter Katie Stallard said people would find the suggestion hard to believe, particularly considering the coincidence around the timing of it.

Police have said a "massive trail" of radiation followed Mr Kovtun and his co-accused, Andrei Lugovoi, across London.

Litvinenko died at a London hotel on November 1st 2006 | File photo

Traces were found in each of the hotel rooms they stayed in, restaurants they visited and even on their plane seats back to Moscow.

The former KGB agent did not deny he and his colleague had met Mr Litvinenko on October 16th 2006 at Itsu restaurant in London - but said Mr Litvinenko had told them he was feeling unwell and had been sick the night before.

Mr Kovtun suggested he had been contaminated when the group shook hands.

He said: "On the night of October 15th he [Litvinenko] was vomiting, he felt sick and he was called an ambulance."

"Next morning he meets up with us - I can imagine that he was all covered in polonium. We shook hands and went to the office together. After that we were leaving traces everywhere. That's it."

On his deathbed, Mr Litvinenko accused Russian President Vladimir Putin of ordering his assassination.

He had been an outspoken critic of the Kremlin and defected to the UK in 2000 - it is thought he then worked for MI6 as an informer.

Mr Kovtun also told the news conference he would do "everything in my power" to testify via videolink at the inquiry into Mr Litvinenko's death.

He said he would take part if he was given "core participant" status and the judge in London considers evidence he believes proves his innocence.

Getting such status would give him access to confidential information being used by the inquiry, which is currently on hold until July 27th.