Ukraine said it has hit two oil refineries in multiple strikes deep inside Russia with patrol boats and other vessels in the Black Sea also hit. This was reported by Qazaqyia.kz citing BBC News.
President Volodymyr Zelensky said the Bashneft-Novoil and Slavneft-Yanos refineries were struck in the attacks aimed at limiting oil revenues Moscow "uses to finance" its war.
Yaroslavl regional governor Mikhail Evraev said Slavneft-Yanos was on fire after what he called the "largest enemy drone attack". He said four people were injured.
Meanwhile, Ukraine said at least 11 people were killed in Russian attacks, and the southern city of Kherson reported a total blackout. Russia said it targeted fuel, energy and transport facilities.
Both Russia and Ukraine have in recent weeks intensified attacks on major cities, energy facilities and warehouses, as the vast front line remains virtually static and all mediation efforts to end the war have brought no breakthrough.
Russian President Vladimir Putin launched a full-scale invasion of Ukraine in February 2022.
Zelensky said on Thursday that the struck Bashneft-Novoil refinery in Russia's Bashkortostan republic was about 1,300km (808 miles) from the Ukrainian border, whereas Slavneft-Yanos was almost 700km (435 miles) away.
The Ukrainian president also said that "two military patrol boats and shadow fleet vessels were hit" in the Black Sea, referring to tankers used by Russia to illegally export sanctioned oil.
"Russia must choose peace," Zelensky said, adding that Ukrainian attacks were "strengthening chances for diplomacy".
Evraev said 93 drones were shot down over Yaroslavl region overnight.
"Falling debris hit the oil refinery's storage tanks. Emergency services are working to extinguish the fire," he said.
BBC Verify confirmed multiple videos and images shared on social media showing huge smoke plumes rising from the refinery. In one of the verified images there appear to be at least four fires at the site.
Energy-generating infrastructure in Yaroslavl has been targeted a number of times by Ukraine.
The authorities in Bashkortostan have not publicly commented on the reported Ukrainian attack on the Bashneft-Novoil refinery on 5 August.
In Ukraine, three people were killed in the town of Balakliya, Kharkiv region, in an overnight Russian drone attack, the country's state emergencies service DSNS said. It said private residential houses were targeted, with fires reported in two buildings.
Kharkiv regional head Oleh Synehubov later said that another two people were killed when drones attacked the train station in Lozova. Another eight people were injured.
Later on Thursday, five people were killed in Russian strikes on the central Dnipropetrovsk region, local officials said.
In the south, the entire city of Kherson is now without electricity after a "critical infrastructure facility" was hit overnight, regional head Oleksandr Prokudin said.
In Ukraine's Black Sea port of Odesa, one person was killed when Russia hit two dry cargo ships.
Meanwhile, the Russian military said its forces intercepted or shot down 605 Ukrainian drones overnight over a number of regions. In its latest operational update, the military said it struck Ukraine's fuel, energy and transport facilities, as well as drone storage sites.
Additional reporting by Peter Mwai and Richard Irvine-Brown, BBC Verify.