Russia has expelled diplomats from 23 countries in retaliation against the West in an escalating spy row, in the biggest wave of tit-for-tat expulsions in recent memory.
The Russian foreign ministry said it had summoned the heads of missions from 23 countries to tell them that some of their diplomats had to leave.
France, Germany, Canada and Poland each said that Russia was expelling four of their diplomats. Other countries including Ukraine, the Netherlands, Sweden, the Czech Republic, Finland, Lithuania and Norway were also told to pull their envoys.
The moves came in retaliation for the coordinated expulsion of Russian diplomats by Britain and its allies over a nerve agent attack against former double agent Sergei Skripal and his daughter Yulia in the English city of Salisbury on March 4.
"This is certainly not a surprise," Dutch Foreign Minister Stef Blok said through a spokeswoman, referring to Moscow's expulsion of two of the country's diplomats.
Britain has said it is "highly likely" that Russia was responsible for the Skripal attack using the Novichok nerve agent developed in the Soviet Union, but Russia has angrily denied any involvement.
After the poisoning, Britain kicked off the global response by announcing it would expel 23 Russian diplomats, suspend high-level diplomatic contact with Moscow and not send any members of its royal family to the 2018 football World Cup hosted by Russia.
Russia then responded by closing a British consulate in Saint Petersburg and the British Council educational and cultural organisation.
In further measures against the UK, the Russian foreign ministry gave Britain a month to cut the number of diplomatic staff in Russia to the same number Russia has in Britain, a move London called "regrettable".
"This doesn't change the facts of the matter: the attempted assassination of two people on British soil, for which there is no alternative conclusion other than that the Russian State was culpable," a spokeswoman for Britain's Foreign Office said.
Two Australian diplomats were expelled, with Prime Minister Malcolm Turnbull saying it was "a disappointing, although not unexpected, reaction by the Russian Government to the decision of the Australian Government to expel two Russian diplomats working as undeclared intelligence officers."
In the Kremlin, President Vladimir Putin presided over a meeting of the country's Security Council which discussed the most recent retaliatory steps against Britain and its allies.
"Russia did not unleash any diplomatic war," Putin's spokesman Dmitry Peskov said. "Russia never initiated any exchange of sanctions."
Moscow announced Thursday that it would expel 60 US diplomats and close the US consulate in Saint Petersburg after the expulsion of its own diplomats and the closure of one of its US consulates.
In all, more than 150 Russian diplomats have been ordered out of the US, EU members, NATO countries and other nations which are accusing Russia of being involved in the Skripal poisoning.
Foreign Minister Sergei Lavrov has warned Moscow's response might "not only" be symmetrical.
On the streets in Saint Petersburg, passersby said they welcomed the decision to shut down the US consulate general.
"This is great news," said Viktor Glushko, 60. "It is about time."
Another man shouted: "Get out of here!" as he passed by the US consulate where staff were seen loading plastic sacks into vehicles Friday.
In Washington, the State Department said there was no justification for the most recent Russian move and that the United States "reserves the right to respond".
US media showed footage of a Russian government plane on the tarmac at Washington's Dulles airport, apparently to begin ferrying the expelled Russians home.
But a State Department official told AFP that Russia has not been asked to cut the headcount at its mission, and so it could apply to accredit new diplomats to its US embassy to replace those leaving.
In London, the Russian Embassy on Friday accused British authorities of "another blatant provocation", claiming they had searched an Aeroflot plane without proper permissions.
"We have no other explanation but that the incident at Heathrow is in one way or another connected with the hostile policy that the UK government is conducting with regard to Russia," they said in a statement.
London's Metropolitan Police said on Twitter that it was aware of the issue.
"Please be advised that Metropolitan Police are not conducting a search of an Airbus inbound from Moscow at Heathrow," they tweeted, without giving further details.
The UK hospital where Skripal and his daughter are being treated said Thursday that Yulia, 33, was "improving rapidly and is no longer in a critical condition", while 66-year-old Sergei remained in a critical but stable condition.