Authorities have managed to contain a fire at Russia's Tuapse oil refinery that broke out after a Ukrainian drone attack, officials in the Krasnodar region said.

According to preliminary information, there are no casualties, they added.

Russian air defenсe and the Black Sea Fleet destroyed 102 Ukrainian drones and six uncrewed boats over the past night, Russia's defence ministry said on Friday morning.

An electrical substation was damaged in Sevastopol as a result of the attack, local governor Mikhail Razvozhaev said on Telegram.

"There will be isolated blackouts," he said.

"In view of the situation, I made a decision to cancel classes in all schools, institutions of secondary vocational education and kindergartens." (Reporting by Reuters; Editing by Clarence Fernandez and Muralikumar Anantharaman)