Theresa May has claimed that Russia's western spy network has been "dismantled" after 23 nations, including the US, joined with Britain to expel more than 130 "diplomats".
The Prime Minister told Vladimir Putin the attempt to "intimidate" Britain with the Salisbury poisonings had "spectacularly backfired" as she hailed "the largest collective expulsion of Russian intelligence officers in history".
Mrs May vowed never to allow President Putin's espionage machine to be rebuilt after the US and other Western allies announced the expulsion of dozens of Russian intelligence officers.
President Donald Trump ordered 60 suspected Russian spies to leave the US - including 12 from the United Nations in New York - while 16 EU countries and six other non-EU members also gave Russians notice to leave. At least two other EU members will follow suit on Tuesday, taking the total to 25 countries.
Mrs May said the unprecedented show of solidarity, which outstripped even Downing Street's expectations after days of intense diplomacy, sent the "strongest signal" to the Kremlin that Russia "cannot continue to flout international law and threaten our security".
The White House said Mr Putin could no longer be in any doubt that "actions have consequences". A total of 114 Russian diplomats were expelled by Britain's allies, adding to the 23 already sent home by the UK last week.
The international response to the Salisbury attacks was described by experts as a "heavy blow" to Russian intelligence gathering.
Donald Tusk, the President of the European Council, said "additional measures" - including more expulsions by more countries - could not be excluded in the "coming days and weeks".
Mrs May said: "President Putin's regime is carrying out acts of aggression against our shared values and interests within our continent and beyond. If the Kremlin's goal is to divide and intimidate the Western alliance, then their efforts have spectacularly backfired."
However, Jeremy Corbyn remained isolated in refusing to directly attribute responsibility for the poisonings of Sergei and Yulia Skripal to the Kremlin, saying only that Moscow was "directly or indirectly" to blame.
Mapped: Russian diplomats expelled from West
He was also accused by one of his own MPs of lying when he said in a Commons debate that he had been a "robust critic" of the Russian government for 20 years.
Labour MP John Woodcock pointed out that after Russia's annexation of part of Ukraine, Mr Corbyn wrote that the invasion was "not unprovoked".
As Australia became the latest country to expel Russian diplomats in a show of support for Britain, Prime Minister Malcolm Turnbull called the Salisbury poisoning a "disgraceful" and "brazen" attack and said his country "cannot and will not stand by and watch when the sovereignty of our allies and partners is threatened".
Mrs May said police investigating the Salisbury attack had now established that 130 people could potentially have been exposed to the Novichok nerve agent, which had been "stockpiled" by Russia in recent years following work on "delivering nerve agents, probably for assassination".
The mass expulsion was greeted with fury in Moscow, which said Britain's allies had "blindly" followed Mrs May's lead, which resulted in "escalating the confrontation".
Mr Putin's spokesman, Dmitry Peskov, hinted that the Kremlin would respond with tit-for-tat expulsions, saying Russia would proceed from the "principle of reciprocity".
A Kremlin spokesman said she had a "surprise" for Boris Johnson, who compared Russia's hosting of the 2018 World Cup to the 1936 Olympics in Nazi Germany.
Maria Zakharova said Mr Johnson "doesn't know any history" and referred to British athletes joining in with Nazi salutes at the Games while the Soviet Union stayed away.
President Trump's tough action, which also included the closure of the Russian consulate in Seattle because of its proximity to a Boeing facility and a submarine base, was welcomed by the Foreign Office particularly after Mr Trump had insisted on congratulating Mr Putin by phone on his recent election win, against his team's advice.
Germany, France and Poland will each expel four Russians, with others deported from Lithuania, the Czech Republic, Denmark, Italy, the Netherlands, Spain, Latvia, Romania, Croatia, Hungary and Estonia. Canada, Australia, Norway, Macedonia, Ukraine, Sweden, Finland and Albania will also expel suspected spies, with Belgium and Ireland confirming they will announce expulsions on Tuesday.
sleepy salisbury murder plot
The Czech ambassador to the US, Hynek Kmonicek, said Russia clearly saw Britain as a "security weak link" because while Russian defectors typically went to the UK, the US or Israel, "they only die in the UK".
Britain had also been hoping Nato would consider expelling Russian officials, but the plans hit a roadblock when Belgium, which only has a handful of diplomats in Moscow, vetoed the move.
Prof Anthony Glees, the director of security and intelligence studies at Buckingham University, said: "It is a heavy blow to the Russia intelligence gathering. They are more on their own than they have ever been."
Mrs May scored a diplomatic victory at a Brussels summit of EU leaders on Thursday. Heads of state and government criticised the Salisbury attack and agreed it was highly probable Russia was responsible.
The action comes after more than a fortnight of mixed messages over America’s willingness to take a tough line on Russia for the Salisbury poisoning.
The White House declined to point the finger at Russia explicitly the day Mrs May linked the Kremlin with the attack during an address in the House of Commons.
Mr Trump also failed to mention that attack during a phone call with Mr Putin last week and at times has not matched critical rhetoric of cabinet colleagues and officials.
Senior US administration officials pushed back on the suggestion they had been sending “mixed messages” on Monday, saying that they stood with Britain over the attack.
A No 10 spokesman said: "We welcome today's actions by our allies, which clearly demonstrate that we all stand shoulder to shoulder in sending the strongest signal to Russia that it cannot continue to flout international law."
Defence Secretary Gavin Williamson, visiting Estonia, also welcomed the expulsions. "I think that is the very best response that we can have because their intention, their aim, is to divide and what we are seeing is the world uniting behind the British stance," he said. "That in itself is a great victory and that sends an exceptionally powerful message to the Kremlin and President Putin."