Early on Sunday a massive oil depot fire was raging near Russia's Black Sea resort of Sochi - blamed by the Russian authorities on a Ukrainian drone attack. Sochi's airport in the same area - Adler district - suspended flights.

Primary oil processing at Russia's Novokuibyshevsk refinery, which is operated by the Rosneft oil company, has been halted since August 2 following a Ukrainian drone attack last week, two industry sources said.

More than 120 firefighters were trying to extinguish a blaze at an oil depot in the Russian city of Sochi that was sparked by a Ukrainian drone attack, regional Governor Veniamin Kondratyev said early on Sunday on the Telegram messaging app.