Authorities in the city called on thousands of residents to evacuate immediately on Friday due to rapidly rising floodwaters.

"The situation remains challenging. In some areas the flood peak is still ahead," Orenburg Governor Denis Pasler said on the Telegram messenger app.

Water was also rising sharply in another Russian region, Kurgan. Floodwaters were approaching the settlement of Baraba, located near the regional centre Kurgan, governor Vadim Shumkov said on his Telegram channel, calling on residents to evacuate.

Shumkov said a deluge could reach Kurgan in the coming days. The level of the Tobol river, which flows through the city, may reach 9-11 metres, he added.

(Reporting by Reuters; Editing by Alex Richardson)