While such a suggestion would normally stretch credulity, samples of his blood were sent to Britain's nuclear research centre at Aldermaston in Berkshire.
The pair remain in hospital in a critical condition.
He was convicted by Russia of treason in 2006 for betraying dozens of spies to British intelligence.
"It is too early to say whether it is certain or not, but it certainly bears all the hallmarks of a Russian attack", he said.
Russia was "in many respects a malign and disruptive force", he added.
A former Russian intelligence agent convicted of spying for Britain is suspected to have been poisoned with an unknown substance in Salisbury, southern England, The Telegraph daily has reported. "We'd certainly have to consider that". "Taking this into account, the embassy has asked the UK Foreign Office for clarifications", the spokesperson said in a statement obtained by Sputnik.
"Police had a good look at the footage and were interested in these two people".
Nearly 2,000 miles separates the Kremlin from Salisbury's Maltings Centre - but revenge, as counter-espionage agents were quick to point out, knows no boundaries. In that case, the British government waited a decade before releasing a report claiming that Russian President Vladimir Putin "probably approved" Litvinenko's murder.
Metropolitan Police Assistant Commissioner Mark Rowley, in an interview with the BBC, also drew parallels to the Litvinenko case. The umbrella tip contained a tiny pellet of ricin, a toxin derived from caster beans that is lethal in tiny doses. "He was doing some strange hand movements, looking up to the sky".
He was pardoned before being flown to Britain as part of a high-profile spy swap between Russia and the United States in 2010.
"Individuals cannot provide unlimited amounts of blood for testing so investigations will be guided by the clinical team", he said.
A spokesperson for Prime Minister Theresa May later added: "The foreign secretary's aides have been clear he was making a reference to diplomatic and political representation to the World Cup".
British police stand guard beside a cordoned-off area in Salisbury.
According to the official, UK media outlets are speculating on the issue.
He was poisoned by radioactive polonium in what British intelligence believes was a Russian state-ordered execution. Then the man went stiff.
Russia has denied knowing anything about the case.
The shadow foreign secretary, Emily Thornberry, said MPs were extremely concerned about the incident in Salisbury, praising the emergency services' bravery given the risks and the history of other poisonings.
Russian double agent Sergei Skripal and his daughter are fighting for their lives after being exposed to a mystery substance.
KGB agents and senior members of Bulgaria's secret police were suspected of being involved in the killing, but Markov's killers have never been brought to justice.