Scores of Russian spies are facing expulsion from Western capitals, as allies rallied in an unprecedented show of support for Britain over the Salisbury nerve agent attack.

Theresa May told MPs that in total more than 100 spies were being sent home from 18 nations in the “largest collective expulsion of Russian intelligence officers in history”.

They include the ejection of 60 spies from the United States as well as intelligence officers operating in Canada, Ukraine, Albania and 14 European Union member states.

The co-ordinated move drew a furious response from Moscow, which accused Western allies of “blindly following the principle of the Euro-Atlantic unity to the detriment of common sense, the norms of civilised inter-state dialogue and the principles of international law”.

Mrs May also told the Commons more than 130 people could have been exposed to the Novichok nerve agent, with more than 50 people assessed in hospital.

Sergei Skripal and his daughter Yulia were left critically ill in hospital following the attack, with the PM saying doctors have indicated their condition is unlikely to change in the near future and they “may never recover fully”.

Labour leader Jeremy Corbyn also said Russia “has a direct or indirect responsibility” for the “outrageous” attack but had offered “denials and diversion” in response to claims and questions over their involvement.

Mr Corbyn was subjected to constant heckling from Tory MPs with former minister Mark Francois bringing proceedings temporarily to a halt when he began whistling the Russian national anthem in a bid to mock the Opposition leader.

The stormy exchanges followed Mrs May earlier telling the Commons that the move to expel diplomats underlined the unity of the West in the face of Russia’s deployment of a nerve agent on British soil.

“Together we have sent a message that we will not tolerate Russia’s continued attempts to flout international law and undermine our values,” she said.

“President Putin’s regime is carrying out acts of aggression against our shared values and interests within our continent and beyond.

“As a sovereign European democracy, the United Kingdom will stand shoulder to shoulder with the EU and with Nato to face down these threats together.”

Speaking at the start of a debate on national security and Russia, she added: “Sergei and Yulia Skripal remain critically ill in hospital.

“Sadly, late last week, doctors indicated that their condition is unlikely to change in the near future, and they may never recover fully.

“This shows the utterly barbaric nature of this act, and the dangers that hundreds of innocent citizens in Salisbury could have faced.”

In Moscow, President Vladimir Putin’s spokesman, Dmitry Peskov, hinted the Kremlin would respond with tit-for-tat expulsions, saying Russia would proceed from the “principle of reciprocity”.

Russia has already ordered 23 British diplomats to leave in response to the expulsion of a similar number of undeclared Russian intelligence officers from the UK.

The Russian foreign ministry said: “This provocative gesture of notorious solidarity with London, made by countries that preferred to follow in London’s footsteps without bothering to look into other circumstances of the incident, merely continues the policy of escalating the confrontation”.

The co-ordinated move came after EU leaders last week backed Mrs May’s assertion that there was “no plausible alternative explanation” other than Russia was responsible for the poisoning of the former double agent and his daughter.

European Council president Donald Tusk said “additional measures” – including further expulsions – could not be excluded “in the coming days and weeks”.

The EU member states taking action include Germany, France, Poland, the Czech Republic, Lithuania, the Netherlands, Denmark, Italy, Latvia, Estonia, Finland, Sweden, Romania and Croatia.

Danish prime minister Lars Lokke Rasmussen said: “Russia has gone too far. An assassination attempt in a European city with a Russian nerve agent is completely unacceptable.”

(PA Graphics)
(PA Graphics)

In addition to the expulsions, the White House said the US was also closing the Russian consulate in Seattle “due to its proximity to one of our submarine bases and Boeing”.

The White House said: “Today’s actions make the United States safer by reducing Russia’s ability to spy on Americans and to conduct covert operations that threaten America’s national security.

“With these steps, the United States and our allies and partners make clear to Russia that its actions have consequences.”

Mr Corbyn, speaking in the Commons, said – based on the analysis conducted by Government scientists – there “can be little doubt” that the nerve agent used in the Salisbury attack was military-grade Novichok of a type manufactured by Russia.

He later said: “There is clear evidence that the Russian state has a case to answer and that they’ve failed to do so, and we can therefore draw no other conclusion other than Russia has a direct or indirect responsibility for this.”

The Government also faced calls to increase defence spending while Tory MP Bob Seely said: “We are in a new cold war.”

Mr Seely also called for a named list for agents of Russian influence in the UK, adding: “Including, let’s tighten up members of the House of Lords, who do work and who’ve been working for some very questionable oligarchs, some of them, I understand.”

Intelligence experts said the expulsions would hit Russian overseas intelligence operations hard.

Professor Anthony Glees, the director of security and intelligence studies at Buckingham University, said: “Their operations will be severely hampered without any doubt but they certainly won’t cease.

“It is still a heavy blow to the Russia intelligence-gathering. They are more on their own than they have ever been.”