A fire broke out early on Wednesday near the airport and not far from an oil depot in the Black Sea resort of Sochi, Russia's RIA news agency reported.

It was not immediately known what caused the fire.

Mash, a Russian news channel on the Telegram messaging app, posted a video of a big column of smoke rising over the city. It said before the fire broke out, explosions were heard.

Reuters could not independently verify the reports. (Reporting by Lidia Kelly in Melbourne; Editing by Christian Schmollinger)