A coroner has written to the government to request a public inquiry in place of an inquest into the death of poisoned spy Alexander Litvinenko.
Sir Robert Owen, presiding over the inquest into Mr Litvinenko's death, has written to the justice secretary after previously ruling he could not hear evidence linked to the alleged involvement of the Russian government in public.
The ruling was published after the coroner accepted an application by the Foreign Office to keep certain information under wraps.
Mr Litvinenko, 43, was poisoned with radioactive polonium-210 while drinking tea at the Millennium Hotel in London's Grosvenor Square in 2006.
A statement from the office said Sir Robert has now written to Chris Grayling to request "a decision be made to order a public inquiry".
A government spokesman said: "We will carefully consider this request."
Mr Litvinenko's widow Marina called for the coroner to order a public inquiry as a matter of urgency after his ruling last month.
The family believe Mr Litvinenko was working for MI6 at the time of his death and was killed on the orders of the Kremlin.
In his earlier ruling, Sir Robert said that excluding key evidence on the issue of Russian involvement would cause him ''grave concern''.
He added: ''Were an inquiry to be held into the circumstances of Mr Litvinenko's death, the relevant material could be taken into account.''