The prime suspect in the killing of Alexander Litvinenko may have offered to give evidence to the public inquiry into the spy's death just to find out more about the proceedings, the hearing was told today.
The suggestion came after Dmitri Kovtun cast doubt on whether he would provide testimony next week as planned.
Kovtun believes he may be committing an offence under Russian law if he goes ahead, inquiry chairman Sir Robert Owen heard.
The Russian was set to give evidence from Moscow by video link early on Monday, Tuesday and Wednesday after he was granted "core participant status" to the inquiry being held in London's Royal Courts of Justice.
But Monday's hearing will start three hours later than planned after Sir Robert gave him a noon deadline to decide whether to take part.
Richard Horwell QC, for the Metropolitan Police, said: "None of this comes as any surprise. It appears Kovtun's request to give evidence was nothing more than an attempt to become a core participant and obtain as much information about these proceedings as he could.
"There's a certain inevitability about what will happen on Monday, and bookmakers' books will be closed.
"But if we do not give him the opportunity to give evidence, then the Russian authorities will blame your withdrawal of the video link, we support the suggestion that he is given until 12 our time on Monday."
Robin Tam QC, counsel to the inquiry, said Kovtun's position appeared to be that he regarded himself as bound by obligations of confidentiality to the Russian investigation, which still continued.
"He has suggested that unless he is discharged from that obligation by the Russian investigating body, he regards himself as unable to give evidence to the inquiry next week."
Sir Robert said: "He declines to assist me. He proffers his sincerest apologies and sets out the advice he has been given by his Russian adviser, that he would be committing an offence under Russian law if he gave evidence unless the Russian authorities gave him permission to do so."
Mr Tam added: "It's been a long time now since he first expressed his desire to give evidence.
"The current position is that a suggestion has been made that he should ask if he can be discharged from that obligation so he can give evidence next week.
"We may have to wait until Monday morning to find if Mr Kovtun is able and willing to give evidence at that time - or we could say, enough is enough, and cancel that."
Sir Robert said: "We were going to reassemble at nine o'clock on Monday, Moscow time is two hours ahead, but in the light of the communications that we have had, I think the better course is to adjourn until 12 on Monday, which gives more time to Mr Kovtun and the investigative committee to sort out their affairs.
"There's a very strong argument for saying they've had far too much time already."
Kovtun and Andrei Lugovoi are suspected of murdering the 43-year-old, who died nearly three weeks after consuming tea laced with polonium-210 in London in November 2006.
They deny any involvement and remain in Russia, having both initially refused to take part in the inquiry.
However in March Kovtun dramatically changed his mind and offered to give evidence.
Sir Robert said he would grant him core participation status and allow him to give evidence if he met a number of conditions.
On his deathbed, Mr Litvinenko accused Russian president Vladimir Putin of ordering his assassination, which the Kremlin denies.
Mr Litvinenko is thought to have been working for British secret service MI6 during his time in the UK.
The former agent for the Russian intelligence service the FSB fled to Britain in 2000 with his wife Marina and son Anatoly to claim asylum, and continued to speak out against the FSB and Mr Putin's regime.
Earlier the hearing was told that Kovtun said to a former fellow restaurant worker that he planned to have Litvinenko poisoned.
The man made the claim in interviews with German police, the inquiry was told.
He did not mention it the first time he was questioned but did so afterwards, saying he was frightened.
The man, known to the inquiry only as D3, had worked with Kovtun in a restaurant in Hamburg in the 1990s, the inquiry heard.
He told German police at his second interview that Kovtun had phoned him out of the blue on October 30 2006 and asked if they could meet. Kovtun asked whether D3 had heard of Litvinenko and he said no.
D3 told police: "He said 'Litvinenko is a traitor, there is blood on his hands'.
"He asked me if I knew a cook who was working in London. He said he had a very expensive poison and needed a cook to administer it to Litvinenko."
D3 said he gave him the name of a former fellow worker of theirs who had wanted to go to England, known to the inquiry only as C2, though he did not know if he had gone to England or not.
D3 told police: "I did not take seriously what Dmitri said, I thought it was just talk. I said, is he crazy, it would be much easier to shoot Litvinenko, jokingly. He said it was meant as an example. I said, 'why did you tell me, of all people?'"
Asked why he had not mentioned it in his first interview, he said: "I was afraid and confused. I hoped the police would sort it out on their own. "
Kovtun had called him and said not to believe what he read in the newspaper, linking him with the case, as it was "just rubbish".
D3 told police: "He has not threatened me. My fear is because he told me about this business and it actually happened."
The inquiry also heard by video link from Germany from a witness known only as D6, who also used to work at the restaurant.
He said Kovtun called him in 2006 after getting his number through another former colleague, D4.
Kovtun asked him if they could meet, which they did not in the end, and asked for a number for C2.
D6 contacted another former colleague, D7, who spoke to C2 and gained agreement that the number could be passed on.
This account was confirmed by D7 in interview with police.