Britain’s ambassador to Russia, Laurie Bristow, was summoned to the Foreign Ministry on Saturday morning, where he was informed of Moscow’s response to London’s claims that Russia is behind the poisoning of Sergei Skripal, a former double agent, and his daughter, Yulia, on March 4 in Salisbury, UK.

The ministry issued a statement saying 23 employees of the British embassy in Moscow have been declared personae non gratae. The diplomats must leave within a week. It also announced the operation of the British Council in Russia will be ceased given its unregulated status.”

In addition, Russia is revoking its agreement on the opening and operation of the UK Consulate General in St. Petersburg due todisparity in the number of consulate facilities of the two countries.”

The British side has been warned that in case further moves of an unfriendly nature towards Russia are implemented, the Russian side reserves the right to take other response measures,” the statement added.

London earlier ordered 23 Russian diplomats to leave the UK by March 20. Including family members, around 80 people will be uprooted from the country, according to Russia’s ambassador to the UK, Alexander Yakovenko.

Bristow told reporters upon leaving the ministry that this crisis has arisen as a result of an appalling attack in the UK,” again linking Skripal’s murder attempt to a chemical weapon developed in Russia.” He added that London’s steps were not directed against the Russian people.”

On Friday, UK Foreign Secretary Boris Johnson suggested that Russian President Vladimir Putin had personally ordered the suspected nerve agent attack – a claim Kremlin spokesman Dmitry Peskov called shocking and unforgivable.”

Sooner or later the British side would have to present some kind of comprehensive evidence [of Russia’s involvement], at least, to their partners [France, the US, Germany], who declared solidarity with London in this situation,” Peskov added.

Moscow has repeatedly offered its full cooperation in investigating the incident, which London claims involved a Soviet-era nerve agent called Novichok. Both nations are members of the Organization for the Prohibition of Chemical Weapons (OPCW), which means that London is obliged to include Moscow in the investigation.

READ MORE: Russian ambassador to UK confirms expelled diplomats will leave on March 20