Claims by a suspect in the killing of Alexander Litvinenko that he wanted to give evidence to the inquiry into the spy's death may have been a "charade", the judge leading the probe has said.
Dmitri Kovtun was due to provide testimony by video link from Moscow but withdrew at the 11th hour.
He was given a deadline by chairman Sir Robert Owen to appear by 9am today but it was finally confirmed this morning that he will not participate.
The inquiry's representative in Moscow told the hearing at the High Court in London that Mr Kovtun had contacted him 45 minutes earlier to say he would not take part today or tomorrow.
Sir Robert gave a detailed account of the probe's dealings with both the suspect and Russian authorities.
He concluded by saying: "This unhappy sequence of events drives me to the conclusion either that Mr Kovtun never in truth intended to give evidence and that this has been a charade.
"Alternatively, if he has at some stage been genuine in his expressed intention to give evidence, obstacles have been put in the way of his doing so.
"In either case I will not have the progress of the inquiry further disrupted."