Kyiv blasts crucial Russian oil refineries in deep long-range strikes (Credit: @ZelenskyyUa)A major oil refinery in Russia's Yaroslavl region caught fire following a drone attack, with Ukrainian President Volodymyr Zelenskyy claiming Kyiv had struck two oil-processing facilities deep inside Russian territory as part of its campaign to weaken Moscow's war economy.Zelenskyy said Ukraine's defence forces targeted the Slavneft-Yanos refinery in Yaroslavl and the Bashneft-Novoil refinery in Bashkortostan.The Yaroslavl facility is located nearly 700 km from the Ukrainian border, while the Bashkortostan refinery lies more than 1,300 km from the front line.The Ukrainian president also shared a video on social media showing thick plumes of smoke rising from the Slavneft-Yanos refinery, located around 280 km northeast of Moscow.Russia reports massive drone attackYaroslavl Governor Mikhail Evraev confirmed that a refinery in the region had caught fire after a drone attack. He said Russian air defence systems intercepted 92 drones in what he described as the largest drone assault the region had faced since the war began.According to Evraev, falling drone debris set three houses on fire, shattered windows in apartment buildings and damaged several vehicles.He said authorities were still verifying whether there had been any casualties.Russia's defence ministry claimed it had intercepted and destroyed 605 Ukrainian drones overnight across several regions, including Yaroslavl, the Moscow region and the Black Sea.The claims could not be independently verified. While verified images showed heavy smoke and flames at the refinery, they did not confirm whether the blaze resulted from a direct strike or falling debris, BBC reported.Kyiv reports Black Sea attacksZelenskyy also said Ukrainian forces struck two Russian military patrol boats and vessels belonging to Russia's so-called shadow fleet operating in the Black Sea.Russia, however, claimed its forces targeted two vessels carrying military cargo at Ukraine's Odesa port. The competing claims came amid another night of intense cross-border attacks.Russian attacks kill six in UkraineUkrainian officials said Russian strikes killed six people overnight. Three people died after drones hit residential buildings in Balakliia, while another three were killed in separate attacks in the Sumy region.According to Reuters, at least 19 people were injured across Sumy, including 12 in Sumy city, where officials said Russia used guided aerial bombs.In southern Kherson, six more people were injured after a drone struck a civilian van.Yaroslavl plant among Russia’s biggestThe Slavneft-Yanos refinery is among Russia's five largest oil-processing facilities. Built in 1961, it employs around 3,500 people and processes nearly 15 million tonnes of crude oil annually, producing petrol, jet fuel and industrial oils.The latest strikes come as Russia has intensified attacks on Kyiv in recent weeks, while Ukraine has increasingly targeted Russian energy infrastructure and other strategic facilities far behind the front lines.