Ukraine attacked a power substation in Russian-occupied Crimea, an oil depot and railway station in Russia's Black Sea port of Novorossiysk and an oil refinery in the port town of Tuapse overnight, a Kyiv intelligence source told Reuters.

Kyiv has stepped up strikes on energy facilities deep inside Russian territory, which they say are legitimate military targets supporting Moscow's 27-month-old war in Ukraine.

Attacks have led to disruptions in refining capacity. Reuters calculations on April 15 showed that Russia had been able to repair some key oil refineries, reducing idled capacity to about 10% from almost 14% at the end of March.

Friday's strikes were a joint operation conducted by the Security Service of Ukraine (SBU) and the HUR military intelligence agency, the source added.

Ukraine launched drones at a refinery in Tuapse, which was already being repaired following an earlier strike, according to the source. "After the new explosions, they will have to start repairs again," the source said.

Russian regional officials reported a fire at the refinery following the attack. It was later extinguished, they said.

Tuapse has an annual capacity of 12 million metric tons (240,000 barrels per day). The refinery had undergone several months of repairs, completed only at the end of April, after a previous fire in January.

Separately, the source said, attacks caused explosions in the port of Novorossiysk, and in the Sevastopol Bay in the Russian-controlled peninsula of Crimea.

The strike on the power station in Sevastopol caused power cuts, the source said. Local governor Mikhail Razvozhaev said the station was damaged and warned of "isolated blackouts."

Russia's defense ministry said its air defenses destroyed 102 Ukrainian aerial drones and six uncrewed naval boats in the Black Sea overnight.