The Russian state security service may have been involved in the death of a fraud whistleblower in Britain three years ago, an inquest has heard.
Alexander Perepilichny, 44, died after collapsing while running near his Surrey home in November 2012.
His death was originally attributed to natural causes but traces of a chemical that can be found in the poisonous plant gelsemium elegans were later found in his stomach.
Lawyers for financial firm Hermitage Capital Management, who previously claimed Perepilichny could have been deliberately killed for helping it uncover a multimillion-dollar fraud involving Russian officials, told a pre-inquest hearing today that the Federalnaya Sluzhba Bezopasnosti or FSB internal security service may be involved.
As the hearing in Woking briefly discussed the scope of the inquiry and whether it should include UK deaths of other prominent Russians, Geoffrey Robertson QC, representing Hermitage, told Senior Surrey Coroner Richard Travers: "We will not be seeking to put forward any evidence that is irrelevant.
"A Russian dies in Britain, that is not relevant. If that Russian dies by an obscure poison known only by the FSB, that is relevant. The FSB is the core element of Russian Government that was involved in the (Alexander) Litvinenko case and may well be involved in this case. It is a secret service that Hermitage has upset and (has) left itself open to reprisals."
He added: "At this stage there is very strong circumstantial evidence that he (Perepilichny) was murdered because of the assistance he was giving to Hermitage."
Mr Robertson also suggested delaying the inquest until after the public inquiry into Mr Litvinenko's death by radioactive poisoning is completed.
Mr Perepilichny collapsed while running near his Weybridge home. A previous pre-inquest hearing was told that before his death he was helping Hermitage uncover a 230 million US dollar (£150m) Russian money laundering operation.
That hearing was told he could have been the victim of a "reprisal killing" in Britain linked to the deaths of Alexander Litvinenko and lawyer Sergei Magnitsky, whose 2009 death in a Russian prison prompted claims he was beaten and then denied medical treatment.
At the earlier hearing in Woking, Hermitage's lawyer Henrietta Hill QC claimed Perepilichny had been on an underworld "hit list" and had received death threats. There was a "clear parallel" between his death and that of Magnitsky, who also worked for Hermitage and died in prison in 2009, she said.
However, Mr Perepilichny's family have said there is no evidence to suggest he was deliberately killed.
Ian Helme, representing his widow and children, said the inquest process was already "taking its toll" and a proposal to widen the scope was "of real concern" and that needed to be taken into account.
The pre-inquest hearing also heard that scientific tests to ascertain what was in Mr Perepilichny's stomach by a Kew Gardens specialist, ordered earlier this year, have yet to be completed.
Professor Monique Simmonds told the court delays caused by internal and external factors at Kew meant the tests would not be competed until the end of October.
Mr Travers said that the "proper time" to rule on the full scope of the inquest was after the test results were known and made no ruling today.
He said: "It is not a question of putting tough decisions off but we need a decision at the right time.
"The right time is once Professor Simmonds' final report has been received."
A further pre-inquest hearing will take place in November, with the full inquest likely to start in February at the earliest.