Mr Bristow told reporters afterwards that Britain had expelled the Russian diplomats only after Moscow had failed to explain how the nerve toxin had got to Salisbury. They remain in a critical condition.
UK Foreign Secretary Boris Johnson upped the stakes Friday when he said it was "overwhelmingly likely" that Russian President Vladimir Putin personally gave the order to use the nerve agent against the Skripals.
The Foreign Secretary's comments earned a scathing rebuke from Mr Putin's spokesman Dmitry Peskov, who said: "We have said on different levels and occasions that Russian Federation has nothing to do with this story".
The Russian statement said the government could take further measures if Britain takes any more "unfriendly" moves toward Russia.
The Russian Foreign Ministry summoned the British ambassador, Laurie Bristow, to its headquarters on Saturdaymorning to inform him of the retaliatory measures.
He said: "Sooner or later, the British will have to show some proof to those "colleagues" who say they are with United Kingdom on this; sooner or later will have to stand up its accusations".
Prime Minister Malcolm Turnbull and Foreign Minister Julie Bishop said in a joint statement on Thursday that it supported Britain "in the strongest terms" and warned that "Australia is considering its responses in support of the United Kingdom".
She tells British lawmakers that the military-grade nerve agent used was identified as belonging to a group of nerve agents known as Novichok and of a type developed by Russian Federation.
Special counsel seeks Trump organization documents
The White House declined to comment specifically on the report and referred questions to the Trump Organization. Trump signed a nonbinding "letter of intent" for the project in 2015 and discussed it three times with Cohen.
Britain's response to the expiry of the deadline and lack of explanation from Moscow was expected to be announced by May in parliament later, after she chaired a meeting of the National Security Council at her Downing Street office in the morning.
The incident revived memories of the fate of Alexander Litvinenko, a Russian dissident who died of Polonium radiation poisoning in London in 2006 in an attack that Britain also blamed on Russia.
The British government said it was expecting the retaliatory expulsions from Russian Federation.
The unidentified mom was allegedly furious that her son was about to marry into the family of Sergei Skripal - whom she considered a traitor for spying on the Russian government.
Western leaders have strongly backed Britain's response.
"You know how many oligarchs find safe haven in London - their money, the real estate, the children sent to secondary schools - and they can not imagine their life without that", he said.
Russia's Investigative Committee said it had launched its own criminal proceedings in connection with the "attempted murder of a Russian citizen, Yulia Skripal" in Salisbury and the "murder" of Glushkov in London. The Swedish and Czech foreign ministers and the Slovak foreign ministry all separately rejected the Russian claim.
Called "newcomer" in English, Novichok refers to a group of powerful and deadly chemical compounds reportedly developed by the Soviet government towards the end of the Cold War in the 1970s and 1980s.