With no major changes reported along the 1000km front line, where a recent push by the Kremlin's forces in eastern and northeastern Ukraine has made only incremental gains, both sides in the war have taken aim at distant infrastructure targets.
In its seventh major attack on Ukrainian power plants since Moscow intensified energy infrastructure attacks three months ago, Russia fired nine missiles and 27 Shahed drones at energy facilities and critical infrastructure in central and eastern Ukraine, the Ukrainian air force said on Thurday.
Air defences intercepted all the drones and five cruise missiles, it said.
The attack hit power structures in the Donetsk, Dnipropetrovsk, Kyiv and Vinnytsia regions of Ukraine, causing "extensive damage", according to national power company Ukrenergo.
Seven workers were injured, it said.
Ukrenergo announced extended blackouts across the country despite electricity imports and help with emergency supplies from European countries.
A Russian barrage in April damaged Kyiv's largest thermal power plant. (AP PHOTO)
Private energy company DTEK said one of its power plants was hit in the overnight attack but did not specify its location.
Three company employees were injured and the plant's equipment was severely damaged, DTEK said on social media.
Among the most damaging recent strikes on Ukraine's energy supply were an April barrage that damaged Kyiv's largest thermal power plant and a massive attack on May 8 that targeted power generation and transmission facilities in several regions.
Rolling blackouts have affected Ukrainian households and industry.
The Russian defence ministry said the strikes aimed at Ukrainian energy facilities that were needed to produce weapons and military equipment.
Ukraine, which is heavily dependent on Western military aid, is developing a small but fast-growing defence industry.
In Russia, meanwhile, authorities in two regions reported fires at oil storage depots after drone attacks, two days after a Ukrainian strike started a huge blaze at another refinery.
Ukraine has in recent months stepped up aerial assaults on Russian soil, targeting refineries and oil terminals in an effort to disrupt the Kremlin's war machine.
The overnight drone attacks were carried out by Ukraine's Security Service, known by its acronym SBU, a Kyiv security official told the Associated Press.
The attacks triggered fires at the facilities, which processed and stored crude oil and its derivatives used to supply the Russian army, the official said.
The official spoke on condition of anonymity because he was not authorised to release the information.
The head of Russia's Adygea region, Murat Kumpilov, said a Ukrainian drone attack sparked a fire at an oil depot in the town of Enem that was later extinguished.
The governor of the Tambov region, Maxim Yegorov, said an oil reservoir went ablaze at an oil depot there.
Krasnodar regional governor Veniamin Kondratyev said a drone hit a private house in the town of Slavyansk, killing a woman.
Russia's defense ministry said air defences downed 15 Ukrainian drones over three regions but did not mention any damage.
The ministry said it has shot down more than 26,000 Ukrainian drones since the start of the war.
