Collapse draws attention

accused the media of “launching a new phase of the anti-russian campaign ongoing in the UK,” adding: “Looks like the script of yet another anti-russian campaign has been already written.”

Earlier, Metropolitan Police assistant commissioner Mark Rowleysaid: “We have to remember that Russian exiles are not immortal, they do all die and there can be a tendency for some conspiracy theories. But we have to be alive to the fact of state threats as illustrated by the Litvinenko case.” Deadly, silent and potentially undetectable, poisons appeal to assassins.

With mystery surrounding the circumstances of ex-spy Sergei Skripal’s collapse following suspected exposure to an unknown substance, attention has once again been drawn to poisonings linked to Russia.

Itwasevenallegedthatarussian hitman was on the loose in the UK following the death of Alexander Perepilichnyy.

Perhaps the most high-profile case of fatal poisoning is that of former Russian secret agent Alexander Litvinenko.

The fierce Kremlin critic died in a London hospital in November 2006 from a fatal dose of the extremely rare radioactive isotope polonium-210.

Polonium-210 also leaves a radioactive trace, which in the Litvinenko case led investigators to Lugovoy.

In 2016 a public inquiry concluded that the killing of Mr Litvinenko had “probably” been carried out with the