The Russian Foreign Ministry said on Saturday that it will be expelling 23 British diplomats from the British Embassy in Moscow within a week, the BBC reported.

This comes in response to Britain’s decision to expel 23 Russian diplomats, following an incident on 4 March, in which a Russian double agent attempted murder in the UK.

Russian ex-spy Sergei Skripal, 66, and his daughter Yulia Skripal, 33, were poisoned with a nerve agent called Novichok, which the UK government says was developed by Russia.

Skripal and his daughter remain critically ill in a hospital in Salisbury, Wiltshire.

The UK Foreign Office said in a statement: "Russia's response doesn't change the facts of the matter - the attempted assassination of two people on British soil, for which there is no alternative conclusion other than that the Russian State was culpable."

British Prime Minister Theresa May blamed Russia for the incident.

"This happened in the UK, but it could have happened anywhere and we are taking a united stance against it,” she said.

Moscow has denied any involvement in the incident.

Earlier this month, the Metropolitan Police launched an investigation into the murder of Russian businessman and exile Nikolai Glushkov, who was found dead in his south London home with “severe compressions to the neck,” reported the BBC.

For the time being, there is no evidence linking the two crimes to one another, the police said, however, they are in the process of contacting Russian exiles to discuss their safety.