Litvinenko inquest in doubt after evidence ruling
The inquest into the 2006 death in London of former KGB spy Alexander Litvinenko has been thrown into doubt.
A coroner is seeking views on whether to hold a form of public inquiry instead, during which evidence about Russia's alleged role in the killing could be heard in secret.
This follows him accepting a Foreign Office application to keep certain information under wraps.
Mr Litvinenko's widow, Marina, said she was "utterly dismayed" by the ruling.
In a written ruling, the coroner Sir Robert Owen said the inquest could not take evidence on the Russian state on grounds of national security.
He also agreed to exclude any material relating to whether the British security and intelligence services could have prevented Mr Litvinenko's death from radioactive poisoning.
Without such material any verdict would be "potentially misleading and unfair", he said.
He said he now wanted to hear submissions from all parties, including Mr Litvinenko's widow and son, on the proposed semi-secret inquiry.
Mrs Litvinenko felt the coroner had made a "decision to abandon his search for the truth about Russian state responsibility for her husband's death", her solicitors said in a statement.
She had previously claimed the UK and Russia were trying to shut down the inquest to preserve trade interests.
'Matter of urgency'
The statement continued: "All those concerned with exposing the truth will be shocked and saddened that a political deal has been done between the two governments to prevent the truth from ever seeing the light of day.
"The only way now that the truth can be exposed will be for the justice secretary to order a full public inquiry which can consider the secret evidence in closed session.
"We will be pressing the coroner immediately to request that such an inquiry should now be established as a matter of urgency."
Mr Litvinenko, 43, died after he had been poisoned with polonium-210 while drinking tea at a London meeting.
He was working for MI6 alongside Spanish spies in the days before his death.
Police have sought the arrest of two Russian nationals in relation to the death - Andrei Lugovoy and Dmitri Kovtun - but the Russian authorities have refused to hand them over.
The inquest has already faced major delays because both the UK and Russian governments have been slow to disclose documents.
In a pre-inquest hearing, Foreign Secretary William Hague asked Sir Robert to exclude material from the eventual hearing under a power called Public Interest Immunity.
The PII process allows ministers to ask courts to withhold information from a hearing if its disclosure could be damaging to national security.
BBC security correspondent Gordon Corera said the government had claimed PII in order to remove certain documents most likely originating with the intelligence services.
'Fair and fearless'
In his ruling, Sir Robert said that he had partly agreed to Mr Hague's request for secrecy in relation to the role of the Russian state and whether the UK could have done anything to prevent the death.
But he said addressing these issues at the inquest without the material could mean a verdict would be potentially misleading and unfair.
Sir Robert said: "My decision to uphold the PII claim... in relation to material relevant to the issue I have listed including those of Russian state responsibility and of preventability, has obvious implications as to the scope of the inquest and the manner in which I should now proceed.
"In this regard it has to be borne in mind that in conducting an inquest I have no power to take evidence in closed proceedings in the absence of the [interested parties]."
Sir Robert said that there was material in the public domain about the events surrounding the death - but considering them alone would be insufficient.
"My provisional view is that to entertain these issues on the basis of the available open evidence, but to disregard the [national security] evidence... would be to fail to discharge my duty to undertake a full, fair and fearless inquiry into the circumstances of Mr Litvinenko's death.
"The same could be said of a decision to remove the issues from scope. But the better course is arguably not to address the issues at all rather than to do so on an incomplete, inadequate and potentially misleading basis."