Lawyers for the widow of murdered Russian dissident Alexander Litvinenko are to call for a detailed inquest to be held into his death.
Marina Litvinenko's legal team will urge St Pancras coroner Dr Andrew Reid to hold an in-depth investigation into how the former KGB agent came to die of radioactive polonium-210 poisoning in a London hospital nearly five years ago.
Scotland Yard is expected to argue in favour of a more limited inquest to avoid prejudicing any future criminal trial of those responsible for the murder. The hearing will also consider whether the inquest should be chaired by a High Court judge and heard by a jury, according to the murdered dissident's friend Alex Goldfarb.
Mr Litvinenko, 43, fell ill shortly after drinking tea during a meeting at a West End hotel with former KGB contacts and died in London's University College Hospital on November 23 2006.
British prosecutors named fellow ex-KGB agent Andrei Lugovoy as the main suspect in his murder, but the Russian authorities have repeatedly refused to send him to face trial in the UK.
Russian president Dmitry Medvedev insisted during a visit to Moscow by Prime Minister David Cameron last month that Mr Lugovoy - now a Russian MP - would never be extradited to Britain.
Mr Goldfarb, who has campaigned for Mr Litvinenko's killers to be brought to justice, said holding a detailed inquest was important both to uncover the truth and to protect the public. "Apart from Mr Litvinenko's death, we have an act of radiological terrorism committed in the centre of London, where hundreds of people, if not thousands, were put at risk," he said. "From the standpoint of public safety it is a very serious matter of public safety and should be explored in depth."
He added: "The police told us directly that they are opposing the (in-depth) inquest for the reason that they want to apprehend Mr Lugovoy. They think that this will either be prejudicial to a criminal trial or it will expose their evidence and witnesses.
"Legally, that doesn't stand up. The inquest does not preclude a criminal trial, which is totally unrealistic because Mr Medvedev told Mr Cameron directly earlier this month that Mr Lugovoy will never be extradited."
A spokesman for the coroner said the pre-inquest review was due to be very short and would focus on legal issues.