It's unclear. Some British media, citing unnamed police sources, are reporting that Yulia Skripal unknowingly brought the Novichok nerve agent to Salisbury in her suitcase on a plane trip from Moscow, arriving in Britain the day before the attack.
Russian Federation denies it was involved.
British Prime Minister Theresa May is seeking a global coalition of countries to punish Moscow, and the U.S., France and Germany have already lined up against Russian Federation over the Skripal attack.
"Any reference or mention of our president in this regard is a shocking and unforgivable breach of diplomatic rules of decent behaviour", Kremlin spokesman Dmitry Peskov said on Friday, according to the agency.
Russian Federation described the UK's position as irresponsible and not backed up by evidence. Its foreign ministry called the allegations by Prime Minister Theresa May "insane".
When asked when the expulsions would happen, Mr Lavrov was quoted as saying: "Soon. Soon. I promise you that".
Macron later told reporters he would decide in the coming days what measures France would take against Russian Federation over the attack.
Collin Sexton, John Petty lead Alabama by Virginia Tech 86-83
The freshman finished 6 of 8 from beyond the arc and hit a buzzer-beating 3 at the half to cut Virginia Tech's lead to 43-41. Alabama responded with a 7-0 spurt, regaining a 36-34 edge when Petty canned a 3-pointer with 3:17 left.
Britain's foreign secretary accused Russian President Vladimir Putin of personally ordering the poisoning of ex-Russian spy Sergei Skripal and his daughter, Yulia, describing it as the most brazen such move since World War II.
The Skripals are in hospital in critical condition after being found unconscious on a bench in the southern English city of Salisbury last week.
"Our quarrel is with Putin's Kremlin, and with his decision, and we think it overwhelmingly likely that it was his decision, to direct the use of a nerve agent on the streets of the United Kingdom, on the streets of Europe, for the first time since the Second World War", Johnson said. Friday's comments from Foreign Secretary Boris Johnson mark the first time that Putin has been blamed directly.
Mr Johnson said: "Now is the moment for [President Vladimir] Putin to jam the lid down and send a signal to people: 'You do this, you're going to die'".
According to the Organization for the Prohibition of Chemical Weapons, there is no record of Novichok nerve agents having been declared by any nation that signed the Chemical Weapons convention. Moscow has denied any responsibility.
President Donald Trump's spokeswoman accused Russian Federation of undermining the security of countries worldwide.