Australia has become the latest country to expel Russian diplomats in a show of support for Britain over the Salisbury nerve agent attack.
Prime minister Malcolm Turnbull called it 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".
Earlier, Mr Turnbull and minister for foreign affairs Julie Bishop issued a joint statement saying two Russian diplomats identified as "undeclared intelligence officers" would be directed to leave the country within seven days.
More than 100 Russian spies are being sent home from more than 20 countries, including 60 from the US and intelligence officers operating in Canada, Ukraine, Norway, Macedonia and Albania, as well as in 16 European Union member states.
Mr Turnbull said the poisoning on Sergei Skripal and his daughter, Yulia, which has left them critically ill, was "an attack on all of us".
He added: "It was an attack on the sovereignty of every nation that respect the rule of law and that is why we are taking this action today with another 23 nations around the world, we are defining this recklessness, this lawlessness, from Russia and expressing in solidarity with the United Kingdom and other nations that share those values that we will not tolerate this type of reckless undermining of international law, this reckless assault on the sovereignty of nations."
Co-ordinated move
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”.
On Monday, Theresa May told the Commons it was the "largest collective expulsion of Russian intelligence officers in history" and said more than 130 people could have been exposed to the Novichok nerve agent, with more than 50 people assessed in hospital.
“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."
In Moscow, Mr 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.” – PA