After the first known offensive use of such a weapon on European soil since World War Two, Britain has pinned the blame on Moscow and given 23 Russians who it said were spies working under diplomatic cover at the London embassy a week to leave.
Speaking after his meeting at the Foreign Office on Friday, British Ambassador Laurie Bristow said the, "crisis has arisen as a result of an appalling attack in the United Kingdom - the attempted murder of two people using a chemical weapon developed in Russian Federation".
It ordered the diplomats to leave within a week.
On Friday, Nato Secretary General Jens Stoltenberg said the alliance had "no reason to doubt the findings and assessments by the British government" which suggested Russian responsibility.
When asked what Britain should do next, Tom Tugendhat, a Conservative lawmaker and chair of the foreign affairs select committee, told the BBC: "I think what we got to do is focus entirely on the Putin regime, the Putin family and the Putin henchmen, and focus on their money, much of which is hidden in Western Europe".
Responding, Mr Putin's spokesman Dmitry Peskov said the accusations were "shocking and unforgivable".
On March 13 Russian Foreign Minister Sergei Lavrov says that Moscow is "not guilty" of the poisoning and is ready to cooperate with London.
The crisis erupted after the Skripals were exposed to a Soviet-designed military grade nerve agent, leaving them in critical condition.
"Instead of submitting such a request, Britain has continued to stage a political performance", Lavrov said.
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Swedish Foreign Minister Margot Wallstrom tweeted that she "forcefully reject (s) unacceptable and unfounded allegation" adding that "Russia should answer United Kingdom questions instead".
Lithuania's foreign minister said the poisoning of Sergei Skripal - which has been blamed on Russian Federation - was a test of the UK's strength and diplomatic links ahead of Brexit.
The Foreign Ministry said Moscow's measures were a response to what it called Britain's "provocative actions and groundless accusations".
In a statement, they threatened to take further measures if Britain takes any more "unfriendly" moves toward Russian Federation.
"We will always do what is necessary to defend ourselves", the ambassador told reporters, according to Reuters.
"It is an assault on United Kingdom sovereignty and any such use by a state party is a clear violation of the Chemical Weapons Convention and a breach of global law".
Skripal is a former colonel in Russian military intelligence who was jailed in his country for betraying agents to Britain's MI6 secret service and moved there in a spy swap in 2010.
They also launched a murder investigation into the death of Nikolai Glushkov, a Russian businessman who was found dead in his London home on Tuesday.
It is believed that the Government has already drawn up a "B-list" of further Russian officials to be expelled if the reaction from Moscow to the measures announced by Ms May are deemed to be "disproportionate".