Andrei Lugovoi is one of at least two Russians who met with Litvinenko in London November 1, the day he fell ill. The Russian secret services defector died three weeks later of radiation poisoning with polonium-210.
"The meeting did not take place for technical reasons cited by [Russian] law enforcement officials," Lugovoi's lawyer Andrei Romashov said, without specifying the reasons.
Russian prosecutors and Scotland Yard detectives, who arrived in Moscow Monday as part of the probe into Litvinenko's murder, planned to question Lugovoi at 2:00 p.m. (11:00 a.m. GMT) Thursday, Romashov said, but declined to mention where.
Litvinenko defected in 2000 and received British citizenship in October of this year.
Scotland Yard said Wednesday that Litvinenko's death was a murder, and preliminary autopsy results showed polonium-210 poisoning was the cause of death.
In late November, Lugovoi visited the British Embassy in Moscow and said he was willing to help Scotland Yard investigate the Litvinenko case.