LONDON -- The British judge investigating the radioactive poisoning death of former Russian agent Alexander Litvinenko on Tuesday accused Russian authorities or a key suspect of interfering with his inquiry.
Robert Owen spoke after suspect Dmitry Kovtun failed to give evidence.
Kovtun had offered to testify by video link from Russia, but at the last minute said he was bound by confidentiality obligations to an ongoing Russian inquiry.
Owen said that either Kovtun's offer of participation had been "a charade" or "obstacles have been put in the way of his doing so."
"Mr. Kovtun has been given every opportunity to give evidence," the judge said. "He has now lost that opportunity."
Litvinenko, a KGB officer-turned-Kremlin critic, died in 2006, three weeks after drinking tea laced with radioactive polonium-210 at a London hotel. On his deathbed, Litvinenko blamed Russian President Vladimir Putin of ordering his assassination -- a claim Moscow denies.
British authorities say there is evidence of Russian state involvement, and police have accused two Russians who met Litvinenko in London, Kovtun and Andrei Lugovoi, of carrying out the killing. Both deny involvement, and Russia refuses to extradite them.
Owen plans to wrap up inquiry hearings this week and issue his findings by the end of the year.
