Russian Federation has refused Britain's demands to explain how Novichok, a nerve agent developed by the Soviet military, was used to strike down Sergei Skripal, 66, and his daughter Yulia, 33, in the southern English city of Salisbury.
She added that any boycott of the soccer World Cup, which Russian Federation would host in June and July, was not an immediate priority.
Prime Minister Theresa May announced this week that 23 Russian diplomats would be expelled from Britain after concluding it was highly probable that Moscow was behind the poisoning, but she stopped short of pointing the finger directly at Putin. British diplomats in Moscow were bracing for a retaliatory order from the Kremlin and were just waiting to be told who had to leave and when.
Russia's ambassador to Britain said Friday the 23 expulsions will reduce staff at the embassy by about 40 percent.
Russian Federation has pledged to respond in kind and has been threatened to expel British diplomats from Moscow. A report in the Telegraph says it was put in the suitcase of Skripal's daughter before she left Russian Federation for Britain to see her father.
Lithuanian Foreign Minister Linas Linkevicius told The Associated Press that the Salisbury attack was a direct challenge to Europe. British police said they were treating Glushkov's death as unexplained, but did not think it was linked to the attack on the Skripals.
On Friday, Russia's Investigative Committee said it had launched its own criminal proceedings in connection with the "attempted murder of a Russian citizen, Yulia Skripal" in Salisbury and what it called the "murder" of Nikolai Glushkov in London.
Russia's envoy to the Organization for the Prohibition of Chemical Weapons told The AP that his country has no stocks of the Novichok group of nerve agents, insisting that Soviet-era research into the agents was totally dismantled before Russian Federation joined the organization.
Shulgin said that Russian Federation expects Britain to provide samples of the nerve agent in line with OPCW rules.
A United Kingdom inquiry found that two Russian agents poisoned Litvinenko at a London hotel bar in 2006 by spiking his tea with highly radioactive polonium-210, and that Putin "probably approved" Litvinenko's killing. Mirzayanov said he revealed the existence of Novichok because he thought it was necessary to deprive Russian Federation of its "deadly secret".
Vil Mirzayanov, who now lives in New Jersey, is quoted in Novaya Gazeta as saying it's unlikely the nerve agent came from another former Soviet country as Russians have suggested.
Mirzayanov revealed details of Russia's chemical weapons in the 1990s because he said he was afraid of their impact.
Corbyn added that Labour did not support Putin and that Russian Federation should be held to account if it was behind the attack. Labour Party leader Jeremy Corbyn said in the Guardian that it's possible that "Russian mafia-like groups", rather than the Russian state, were responsible.