Ukraine said it had carried out multiple long-range strikes targeting two oil refineries deep inside Russia, while also hitting patrol boats and other vessels in the Black Sea.

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, BBC reported.

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.