Relations between London and Moscow went into a downward spiral following accusations against Russia of allegedly using nerve agent against its former spy Sergei Skripal, living in Salisbury. The accusations, denied by Moscow, spurred a mass expulsion of diplomats, initiated by London.

The UK government has ordered British military and intelligence agencies to keep a watchful eye on the movements of Russian Embassy personnel and its cars both with and without diplomatic numbers, the Daily Mirror reported citing a secret memo it obtained. The memo reportedly instructs staff to detect and record the movements of Russian diplomatic cars in the UK, including data on their licence plates, the direction of movements, and number of passengers.

Neither Russian nor British officials have commented on the leak so far.

The Mirror reported citing the document, that the UK government fears Moscow might use the diplomats, who stayed in the country after the mass expulsion in March 2018, to run its intelligence operations in the country. An anonymous "senor source" told the newspaper that the expulsion of Russian diplomats "absolutely smashed" Moscow's alleged spying network in the UK and added that now London is working on preventing its restoration.

"It will take Russia years to build up its capability in the UK, and repeated attempts to begin that process have been stopped. So suspicion falls upon diplomats who remain at the embassy", the source said.

READ MORE: Russian Embassy: UK Spy Agencies Involved in Incidents With Russian Nationals

The UK, as well as a number of other Western states, expelled Russian diplomats over Moscow's alleged involvement in the poisoning of former Russian spy Sergei Skripal and his daughter in Salisbury. London accused Russian intelligence officers of attempting to poison both Skripals, without presenting any substantial proof. Moscow denied the accusations, slammed the expulsion of diplomats, and answered reciprocally to the moves by the West.