British authorities are facing calls to reopen an investigation into the sudden death of a Russian whistleblower more than a decade ago amid fears he died of a poison similar to the one that killed Alexei Navalny.

Businessman Alexander Perepilichny, who uncovered organised crime and corruption in Russia, collapsed and died while out jogging near his home in Weybridge, Surrey, in 2012.

An inquest six years later found the 44-year-old died from natural causes, but said he may have been poisoned after suffering vomiting symptoms.

Despite police ruling out foul play at the time, traces of a chemical that can be found in the ultra-rare poisonous plant gelsemium elegans were later discovered in his stomach. 

Financial firm Hermitage Capital Management claimed at the time that he could have been killed deliberately for helping it uncover a multimillion-pound fraud involving Russian officials. 

However, the coroner pointed to Surrey Police for a series of blunders that led to a lack of evidence. 

On Saturday, the UK, along with Sweden, Germany, the Netherlands and France, accused the Russian state of killing 47-year-old Navalny in a Siberian colony.

Navalny had been sentenced to 19 years' imprisonment on dubious embezzlement charges. His death was announced by the Russian state on February 16, 2024. At the time, his allies accused the Kremlin of murdering him because of the political threat he posed.

In their joint statement, the five nations said laboratory analysis found traces of epibatidine in Navalny's body, a toxin associated with South American dart frogs.

Bill Browder, who helped Perepilichny expose a $230m (£142m) money-laundering operation in Russia, said he was struck by the similarities between the two deaths.

He told The Telegraph: 'We were trying to determine what type of poison was used on Alexander Perepilichny in 2012, and with this new information on the Navalny poisoning, it has many similarities.

'It's a shame that the law enforcement authorities in Surrey were so quick to conclude that it wasn't a suspicious death and therefore [did] not preserve the evidence. 

'In light of this new evidence in the Navalny case and all the suspicious circumstances surrounding the death of Alexander... I would hope that the UK would reopen the case that they so negligently closed for "lack of crime".' 

The 2018 inquest heard that police had lost or disregarded evidence, including the contents of Perepilichny’s stomach, that could have led to a different conclusion.

Surrey Police also failed to check CCTV from the area in which Perepilichny collapsed. 

Epibatidine is only found in nature on the skin of the Ecuadorian dart frog and results in a painful death of paralysis and respiratory arrest if ingested. It can also be produced synthetically.

Yulia Navalnaya, the widow of Navalny said on Sunday night that Vladimir Putin 'must be held accountable'.

She thanked Britain and its allies for establishing that his death two years ago is likely to have been caused by the neurotoxin.