Early on Saturday, Russia's Ministry of Foreign Affairs announced it had ordered the British diplomats to leave within a week and indicated it could take further action should there be what it called more "unfriendly" moves.
British Ambassador Laurie Bristow was called to the Foreign Ministry Saturday to be informed of the moves. "Twenty three diplomatic staff at the British embassy in Moscow are declared persona non grata and to be expelled within a week", said a statement. Both are in hospital in critical condition.
His office said a united response with European and transatlantic allies was needed, but quite what France might do remains unclear, especially as Macron has sought to turn a new leaf in relations with Russian Federation since coming to office past year.
British police appealed Saturday for witnesses who can help investigators reconstruct the Skripals' movements in the crucial hours before they were found unconscious. He said Britain must defend itself.
Russian Federation criticized the "hysterical atmosphere" at the meeting, and has repeatedly denied involvement in the poisoning.
"But we will always do what is necessary to defend ourselves, our allies, and our values against an attack of this sort, which is an attack not only on the United Kingdom, but upon the worldwide rules-based system, on which all countries, all countries including Russian Federation, depend for their safety and security".
Foreign Minister Sergei Lavrov has been speaking on the issue at an event in Moscow, although Russian media reports of what he has said have been conflicting.
"Russia's failure to address the legitimate request by the United Kingdom government further underlines its responsibility", it said.
Bristow told reporters afterwards that the crisis had arisen after "the attempted murder of two people using a chemical weapon developed in Russia".
Russia has now denied that any program under the name Novichok ever existed, despite the evidence presented two decades ago by the Russian scientist Vil Mirzayanov, who revealed its existence after becoming concerned it violated Russia's commitments to the Chemical Weapons Convention.
France initially hesitated in fully backing Britain's position that Russian Federation was to blame for a nerve agent attack on a former spy living in England. No explanation as to how this agent came to be used in the United Kingdom; no explanation as to why Russian Federation has an undeclared chemical weapons programme in contravention of worldwide law.
"We call on Russian Federation to live up to its responsibilities as a member of the U.N. Security Council to uphold global peace and security", they said. "Any reference or mentioning of our President is nothing else but shocking and unpardonable diplomatic misconduct".
Suggestions by Russia's ambassador to the European Union that the poisoning could have been carried out by Britain were dismissed as "satirical".
Opposition lawmakers are calling on the British government to clamp down on the illicitly gained money of wealthy Russians in Britain. There's no evidence at this stage that his death and the attack on the Skripals are linked, it said.
Russian President Vladimir Putin is dismissing British accusations of Russia's involvement in an ex-spy's poisoning as "nonsense", adding that Moscow is ready to cooperate with London in the probe.
Putin, a former KGB spy who is poised to win a fourth term in an election on Sunday, has so far only said publicly that Britain should get to the bottom of what has happened. With Russian help, Syrian forces have stepped up their offensive on rebel-held areas in recent days, leaving many dead.