"They’re contacting all the critical national infrastructure operators. They’ve been in touch with National Grid [electricity and gas utilities company] with guidance," the source was quoted as saying by the newspaper.
The National Grid was warned last week by the National Cyber Security Centre (NCSC) and informed about how to improve security measures to prevent a blackout, the newspaper added.
READ MORE: UK Has Evidence Russia Stockpiling Novichok for 10 Years - Foreign Ministry
The security services also reportedly warned the Sellafield nuclear power plant, government departments and hospitals of the National Health Service (NHS) of the possible hacking ordered by Moscow.
Relations between Moscow and London deteriorated in early March after former Russian intelligence officer Sergei Skripal and his daughter were found unconscious in a shopping center in Salisbury, England.
UK Prime Minister Theresa May announced that it was "highly likely" that Russia was responsible for the incident, since the two were poisoned with a Novichok-class nerve agent that was developed in the Soviet Union.
READ MORE: Boris Johnson Slams Moscow's Response to Expulsion of Russian Diplomats From UK
On Wednesday, May went on to announce a package of anti-Russia measures, including the expulsion of Russian diplomats from the country, and the suspension of bilateral contacts between London and Moscow. On Saturday, Russia announced retaliatory measures against the United Kingdom, declaring 23 employees of the UK Embassy in Moscow personae non-gratae in response to London's move.
READ MORE: Russia Mulls Response to UK Over 'Losses' Caused by Diplomat's Expulsion
The ministry also revoked its agreement on opening and operation of the UK Consulate General in the Russian city of St. Petersburg and said that the activities of the British Council in Russia had been terminated.
