Ukraine on Wednesday claimed one of its most extensive long-range drone offensives since the war began, saying it struck three Russian oil refineries, key petroleum infrastructure, military facilities and tankers in the Sea of Azov during overnight attacks. Russian officials also confirmed the strikes across multiple regions, saying air defences intercepted hundreds of Ukrainian drones, though they acknowledged damage in several areas.The strikes, reported by both Ukrainian and Russian officials, stretched from areas near the Ukrainian border to Russia's Urals region, highlighting Kyiv's continued efforts to target Moscow's energy infrastructure and military logistics deep inside Russian territory.In separate statements, Ukraine's General Staff and Special Operations Forces said drones hit the TANECO and TAIF-NK oil refineries in Nizhnekamsk, Tatarstan, the Saratov oil refinery, the Borisoglebsk military airbase in Russia's Voronezh region, and a petroleum products pumping station in Bashkortostan.Ukraine also said it had struck nine oil tankers in the Sea of Azov, describing them as part of a key supply route supporting Russian forces in Crimea and other Russian-controlled areas of southern Ukraine.Russian authorities acknowledged attacks in Tatarstan, Saratov and Voronezh, although they did not specify the exact targets that were hit. Russia's defence ministry said its air defences had destroyed 415 Ukrainian drones overnight.The extent of the damage at the targeted facilities could not be independently verified.The latest operation comes just days after Ukraine said it struck Russia's largest oil refinery in Omsk, around 2,700 kilometres from Ukrainian-held territory in Siberia.According to Ukraine's military, that strike sparked a fire at the refinery, while Omsk Governor Vitaly Khotsenko confirmed the attack and said Russian air defences had intercepted most of the drones involved.There were no reported casualties in Omsk, and emergency services remained at the scene. The full extent of the damage was not immediately known.The TANECO refinery in Tatarstan is regarded as one of Russia's most technologically advanced refining facilities, equipped with hydrocracking, catalytic cracking and delayed coking units.Industry data shows TANECO processed 17 million tonnes of crude oil in 2024, while the nearby TAIF-NK refinery processed 6.6 million tonnes, equivalent to around 132,000 barrels per day.Local authorities in Tatarstan, cited by Russian media, said several people were wounded in the strikes on Nizhnekamsk.Additionally, Russia also launched overnight drone and missile attacks across Ukraine, killing three people, including one in Kyiv, where powerful explosions rocked the capital for the second consecutive night. In Kharkiv, mayor Ihor Terekhov said two people were killed and 20 others injured in a wave of strikes. Authorities noted that several explosions were heard in Kyiv shortly after midnight before an air raid alert was issued, an unusual sequence that left little time for civilians to seek shelter.In the Ukrainian attacks on Russia, Saratov Governor Roman Busargin said one person was killed and several others were injured after what he described as a strike on 'civilian industrial sites.'Russia's state-controlled energy giant Gazprom also said drones targeted the Krasnodarskaya pumping station, a facility that helps transport gas to Turkey through the Blue Stream pipeline, adding that gas exports had not been disrupted.