Ukrainian forces fired more than 30 drones in a renewed assault over the weekend as Russian forces lost at least an entire brigade in their push for the eastern town of Avdiivka, officials said. The Russian air defence systems destroyed 36 Ukrainian unmanned aerial vehicles over the Black Sea and the northwestern part of the Crimean peninsula, its defence ministry wrote on Telegram on Sunday, accusing Kyiv of carrying out a “terrorist attack”. In a separate incident, local officials in southern Russia’s Krasnodar region near the Black Sea said an oil refinery was hit and set ablaze in the early hours of Sunday but did not explain what caused the fire. Several local media outlets said that the fire was caused by a drone strike or a crashed drone’s debris. Officials in Kyiv have not issued a comment on the Russian defence ministry’s claims. The war-hit nation rarely acknowledges responsibility for attacks on Russia and Russian-occupied territories but has admitted that striking targets there helps its counteroffensive. The recent months have seen drone strikes and shelling on the Russian border regions and illegally annexed Crimea peninsula as a regular part of the continuing military offensive. This comes as Ukrainian president Volodymyr Zelensky said Vladimir Putin has lost “at least a brigade” of troops in his offensive push towards the Ukrainian town of Avdiivka. “The invaders made several attempts to surround Avdiivka, but each time our soldiers stopped them and threw them back, causing painful losses. In these cases, the enemy lost at least a brigade,” Mr Zelensky said. Avdiivka, about 25km (16 miles) from Russian-occupied Donetsk, is surrounded by Russian-held territory to the north, east and south, leaving only its west for Kyiv’s troops to resupply and evacuate people. In its latest push for the coke town, Ukraine claimed that Russia is pouring a huge number of forces. The offensive from Russia was renewed in mid-October as tanks and heavy military vehicles were seen heading for the town. Russian forces have since tried to shell Ukrainian positions with constant barrages of artillery, waves of troops and fighting vehicles. But these losses being borne by Mr Putin are likely among some of the highest Russia has seen this year, the British Ministry of Defence said in its intelligence update on the war, claiming that Moscow has probably committed elements of up to eight brigades to the fighting which is “heavy but inconclusive”. The British intelligence claimed that the Russian military bloggers have been “harshly critical” of the tactics Russia has deployed in the Avdiivka operation. Elsewhere on the war front, the Ukraine’s Air Force said its forces shot down five Iranian-made Shahed exploding drones fired by Russia overnight. Another four police officers were wounded when a shell fired by Russian troops exploded near their car in the city of Siversk, located in the partly occupied Donetsk province close to the front line in the country’s east where Ukrainian and Russian forces were locked in a battle for control. Read More Russia-Ukraine war: Putin ally Lukashenko warns of ‘serious stalemate’ If Putin dies, this is what would happen in Russia War-weary mothers, wives and children of Ukrainian soldiers demand a cap on military service time