"We will not be intimidated by the lack of light. We have gone through more than that, and we will survive now," Razvozhayev said in a Telegram message to the public.

"The enemy is again striking vilely, trying to deprive us of our usual living conditions and sow panic."

He said a "special regime" had been put in place at the energy facilities as the damage was assessed and that all emergency services are on full alert.

Those living in Sevastopol were told to introduce power-saving measures including saving mobile phone battery by turning the screen brightness down and switching off background apps.

They were also urged to check on elderly neighbours throughout the day, when temperatures are expected to reach 30C.

Robert Brovdi, commander of Ukraine's Unmanned Systems Forces, said on Wednesday drones had targeted 48 operational and planned military sites.

He said that the main power substation of Sevastopol had been hit during the attacks.

Explosions had also been heard in Bakhchisarai, Kerch and in the area of Mount Ai-Petri, where the radio engineering battalion of the Russian Aerospace Forces is based.