Police in Salisbury launched a major investigation last week after former Russian double agent Sergei Skripal, 66, and his daughter Yulia, 33, were found slumped on a bench on March 4.
The pair are in a critical but stable condition in intensive care – while Detective Sergeant Nick Bailey, who was part of the initial police response, also remains in a serious but stable condition after racing to the aide of the victims.
The episode has left Britain’s relations with Moscow, which were already under severe strain, at breaking point after it was revealed the deadly toxin was a military-grade nerve agent.
In an extraordinary statement in the Commons on Monday, Theresa May told MPs it was “highly likely” Russia was responsible for the poisoning.
She said: “It is now clear that Mr Skripal and his daughter were poisoned with a military-grade nerve agent of a type developed by Russia.
“Based on the positive identification of this chemical agent by world-leading experts at the defence, science and technology agency our knowledge that Russia has previously produced this agent, and would still be capable of doing so, Russia’s record of conducting state-sponsored assassinations, and our assessment that Russia views some defectors as legitimate targets for assassinations, the Government has concluded that it is highly likely that Russia is responsible for the attack against Sergei and Yulia Skripal.”
Her comments provoked a furious backlash from officials in Russia, serving only to ramp up tensions that war could break out between the UK and Russia.
The Russian Embassy in the UK accused the UK Government of playing “a very dangerous game” with Russia, as World War 3 fears mounted.
In a statement, the Embassy said: “Current policy of the UK Government towards Russia is a very dangerous game played with the British public opinion, which not only sends the investigation upon an unhelpful political track but also bears the risk of more serious long-term consequences for our relations.”
World War 3: Theresa May and Vladimir Putin could go to war
It is now clear that Mr Skripal and his daughter were poisoned with a military-grade nerve agent of a type developed by Russia.
The Embassy also lambasted the UK for its “unfounded accusations” and labelled events as a “source of concern”.
The statement added: “Literally the next day after the first reports on the poisoning of Mr Skripal and his daughter the Embassy officially requested the Foreign Office to provide information on their health situation and the investigation.
“This is important to us since his issue has become quite a negative factor for the relations between our countries due to the unfounded accusations against Russia advanced by the media.
“British officials don’t provide any additional information and don’t distance themselves from the media campaign.
“The investigation is being concluded in a non-transparent manner, whenever for the Russian side nor for the public.
“Quite naturally, this is a source of concern.”
Russian news agencies also reported Mrs May’s comments were politically motivated and based on a provocation.
The TASS news agency quoted Russian Foreign Ministry spokeswoman Maria Zakharova as saying: “It is a circus show in the British parliament.
“The conclusion is obvious: It’s another political information campaign, based on a provocation.”
And President Vladimir Putin dismissed questions about the Skripals when he was confronted during an election campaign visit, telling the BBC: “Get to the bottom of things there, then we’ll discuss this.”
World War 3: Russia has denied knowledge of the spy nerve agent attack
World War 3: Theresa May set Russia a deadline of midnight on Tuesday
The British PM set Russia a deadline of midnight on Tuesday for Moscow to explain whether it was behind the attack or had lost control of its stockpile of the poison.
Failure to provide a “credible” response would lead her to view the incident as “an unlawful use of force by the Russian State against the United Kingdom”, sparking unspecified measures in reprisal.
Tory MP Tom Tugendhat lashed out at officials, claiming the poisoning was akin to an act of war.
He said: “This, if not an act of war, was certainly a war-like act by the Russian Federation.
“This is not the first we’ve seen and while some in this house have stayed silent and decided to join the information warfare that that state is conducting against us and our allies, we have seen them invade countries in the East, attack allies, attempt to kill prime minister and even now they are backing the murderous Assad regime which has no problem gassing its own people.”