Moscow: One of the suspects in the murder of Alexander Litvinenko claimed on Wednesday that the ex-spy accidentally poisoned himself.

Businessman Dmitry Kovtun and a second Russian, former Kremlin bodyguard Andrei Lugovoi, are wanted by British police for allegedly poisoning Litvinenko in a London hotel using tea laced with polonium-210, a radioactive isotope.

Kovtun, who cannot leave Russia due to an international arrest warrant, told journalists in Moscow that former Russian security agent Litvinenko was already ill before he met the duo in October 2006 and had most likely unwittingly caused his own death.

“Litvinenko told me that he would not eat anything because the night before he got terrible poisoning, was throwing up all night, and called an ambulance,” Kovtun said as he laid out his defence before giving testimony to a British inquiry.

“That proves our total innocence, that he had already come into contact with polonium, perhaps several days before our meeting,” he said.

“I am more than sure that (Litvinenko) was dealing with polonium without knowing it,” Kovtun said, describing his death as an “accidental suicide”.

“Maybe there was some kind of polonium leak and it was gradually accumulating in his body,” he said. “I don’t know if he had it with him of if somebody gave him something that he carried with him.”

“Where he got the polonium from, that is the question,” Kovtun said.

Kovtun said the trace of polonium he and Lugovoi left in London stems from meeting Litvinenko, when they shook his hand, and that he escaped the worst effects of poisoning due to the timely intervention by Russian doctors.

“Our doctors took measures in time,” he said. “So far, there have not been serious consequences.”

Kovtun last month unexpectedly reversed a decision not to participate in a British inquiry into Litvinenko’s death, which is looking into possible Russian state involvement in the murder.

He demanded that he be granted “core participant” status in the probe in order to scrutinise classified police evidence into the killing that he has consistently denied any involvement in.

“If I don’t get this status, I will not participate,” Kovtun said.

He said he has until May 22 to answer in writing nine questions sent to him by an assistant to Judge Robert Owen, which pertain to his background, his relationship with Litvinenko and Lugovoi, and information about polonium and traces left around London.

If a decision is then made to give him the status of a “core participant”, Kovtun will participate in the inquiry via a video link on July 27, he said.

The inquiry had initially been expected to conclude at the end of March but Kovtun’s agreement to cooperate and delays in other witnesses testifying via video-link meant the hearings will drag on.

A report with the inquiry’s findings is due to be published by the end of the year.

Litvinenko died in a London hospital on November 23, 2006, some three weeks after meeting Kovtun and Lugovoi.

In a letter dictated from his deathbed, he accused Russian President Vladimir Putin of having ordered his murder.