Hugh Davies, the barrister to the inquest, revealed that almost a year after it was invited to participate in the inquest, the Russian government had applied to be represented. On Wednesday, Mr Davies explained a letter was received requesting that the Investigative Committee of the Russian Federation - sometimes compared with the American FBI - be granted "interested-person status" at the inquest in May.

He added that, having examined documents supplied by the British government, the inquiry team had failed to find evidence that supported a wide variety of theories including claims Mr Litvinenko had been murdered by the Russian oligarch Boris Berezovsky, the Spanish mafia, Italian academic Mario Scaramella or Chechen organisations.