Russian Federation denies involvement and had warned for days that it would respond to the U.K.'s expulsion of 40 percent of its diplomats in London.
Tensions between Russian Federation and the West continued to ramp up as France, Germany, Britain and the US jointly accused Russian Federation of involvement in the attack on Sergei Skripal and his daughter in Salisbury in early March, which they said involved the first "offensive use" of a nerve agent in Europe since the Second World War.
They include Moscow's intelligence services, a propaganda organisation and businessman Evgeny Prigozhin, one of 13 Russian nationals charged with interfering with U.S. elections and political processes by Special Counsel Robert Mueller.
"All the responsibility for the deterioration of the Russia-U.K. relationship lies with the current political leadership of Britain".
"The use of a chemical agent banned by global conventions on United Kingdom territory is particularly serious", he continued.
The source of the nerve agent - which Britain says is Soviet-made Novichok - is unclear, as is the way it was administered.
"I want to state with all possible certainty that the Soviet Union or Russian Federation had no programmes to develop a toxic agent called Novichok", he told Interfax news agency.
Later, deputy foreign minister Sergei Ryabkov claimed both the Soviet Union and Russian Federation "had no programmes" to develop novichok.
Skripal was sentenced to 13 years in prison in 2006 for spying for Britain, according to Russian state media accounts of the closed hearing.
"Nobody saw even the pictures of these people in a hospital - whether they are alive or maybe they are in good health".
Ms May has directly accused President Vladimir Putin of being behind the attack.
In a statement, the Russian Defence ministry said: "Fishwife's rhetoric demonstrated today by the head of the British Defense Ministry Gavin Williamson, perfectly characterises an extreme degree of his intellectual impotence".
Putin, who took over as Kremlin chief from Boris Yeltsin on the last day of 1999, has tried to claw back some of the clout that Moscow lost when the Soviet Union collapsed in 1991.
March 5 - Police say two people in Salisbury are being treated for suspected exposure to an unknown substance.
Lavrov said Russia's response would come "very soon" but be conveyed to British officials first, an apparent contradiction of an earlier report by state news agency RIA that said Lavrov had promised to expel British diplomats.
At an urgent meeting of the Security Council in NY on Wednesday, the USA joined Britain in condemning Russian Federation, pledging to stand in "absolute solidarity with Great Britain".
A Russian lawmaker is warning Britain against escalating the crisis over the poisoning of a former Russian spy.
Mr Yakovenko said that Britain should "explain what they are doing in this secret chemical laboratory" at Porton Down, which he said was only a few miles from the site of the Salisbury attack. "Amazing, frankly", Scaparrotti added.
Opponents of President Vladimir Putin used graffiti on Thursday to take an ironic swipe at Russian Federation over the nerve toxin attack on a former double agent.