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.

More than 100 agents are being sent home from 23 countries in what Theresa May called the “largest collective expulsion of Russian intelligence officers in history”.

They include 60 from the US and intelligence officers operating in Canada, Ukraine, Norway, Macedonia and Albania, as well as in 16 European Union member states.

On Monday night, Australia became the latest country to back the UK by expelling two Russian diplomats.

Prime Minister Malcolm Turnbull and minister for foreign affairs Julie Bishop issued a statement saying two Russian diplomats identified as “undeclared intelligence officers” would be directed to leave the country within seven days.

The statement added: “This decision reflects the shocking nature of the attack – the first offensive use of chemical weapons in Europe since the Second World War, involving a highly lethal substance in a populated area, endangering countless other members of the community.

“It takes into account advice from the UK Government that the substance used on 4 March was a military-grade nerve agent of a type developed by Russia. Such an attack cannot be tolerated by any sovereign nation. We strongly support the call on Russia to disclose the full extent of its chemical weapons programme in accordance with international law.

“This attack is part of a pattern of reckless and deliberate conduct by the Russian state that constitutes a growing threat to international security, global non-proliferation rules against the use of chemical weapons, the rights of other sovereign nations and the international rules-based order that underpins them.

(PA Graphics)
(PA Graphics)

Earlier, 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 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 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 to mock the Opposition leader.

The stormy exchanges came after Mrs May told the Commons 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.”

Mrs May said the UK had information indicating Russia has investigated ways of delivering nerve agents, probably for assassination, and has produced and stockpiled small quantities of Novichok as part of this programme.

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 Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany, Hungary, Italy, Latvia, Lithuania, the Netherlands, Poland, Romania, Spain and Sweden.

Foreign Secretary Boris Johnson said countries of the world “have come together in numbers far greater than Putin could possibly have imagined and they are saying enough is enough”.

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.”

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 that, based on 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 than Russia has a direct or indirect responsibility for this.”

The Government 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 of 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.”

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.”