Ukraine has scored further hits in systematic drone attacks on Russian oil facilities, according to the Ukrainian secret service.
Drones triggered a fire at the Ryazan refinery south-east of Moscow during the night, the governor of the region, Pavel Malkov, wrote on Telegram on Wednesday morning.
Three drones struck the factory, which belongs to Russia's largest oil company Rosneft, media reports said.
The oil refinery in Novoshakhtinsk in the Rostov-on-Don region was also hit, with Governor Vasily Golubev saying that the technical facilities had been shut down. According to the company, the plant in Novoshakhtinsk is the largest manufacturer of oil products in southern Russia.
The night before, Ukrainian aircraft had already caused a fire at the Kstovo refinery, which belongs to the Lukoil Group, near Nizhny Novgorod on the Volga.
A drone also caused a fire at a tank farm in the south-west Russian region of Oryol, the state news agency TASS reported. The Kirishi refinery near St Petersburg was also attacked on both nights. According to regional authorities, the drones were intercepted there. There was no information about damage.
"We are systematically implementing a well-calculated strategy to reduce the economic potential of the Russian Federation," a source in the Ukrainian secret service SBU told the news portal Ukrainska Pravda on Wednesday. "Our task is to deprive the enemy of resources."
The fuel supply for the military is to be hit, as well as the inflow of oil revenues, which Russia is channelling into the war and the killing of Ukrainian citizens.
Ukraine hopes that the attacks will noticeably damage fuel production in Russia. "Sowing in Russia will be very difficult, which means that food prices will rise drastically from mid-summer," former deputy interior minister Anton Gerashchenko posted on the social media network X, formerly Twitter.
Fuel shortages could also drive up prices for other goods. Using the example of the Kstovo refinery, Gerashchenko calculated that up to 10% of Russian petrol production could be lost in the event of a shutdown.
According to the Russian Ministry of Defence in Moscow, air defence intercepted 58 Ukrainian drones overnight. A total of 29 aircraft were shot down over the Voronezh region alone, and a further 11 over the Belgorod region.
The Russian army also reported further Ukrainian drone attacks during the day.
The military does not appear to have found a real means of combating the advanced drones from Ukraine.
"Our soldiers are doing everything necessary," said Kremlin spokesman Dmitry Peskov, according to TASS. The air defence system is working, he said. Whether industrial targets need to be better protected is a question for the Ministry of Defence, he said.
Russian President Vladimir Putin said in a TV interview that the attacks were intended to disrupt the presidential election scheduled for this weekend.
Several people were killed and others injured in renewed Russian attacks in various Ukranian regions overnight, local authorities said on Wednesday.
Ten people were pulled from the rubble after a residential building in the north-eastern Ukrainian city of Sumy was severely damaged by a Russian drone attack, the regional administration said on Telegram.
Eight of them suffered injuries to different degrees, according to preliminary information. "Unfortunately one person has been killed," it said.
Thirty flats in the five-storey building were damaged in the attack, it said, with half of them completely damaged.
It comes after five underage children were injured in a bomb attack in the Velyka Pysarivka district, the Sumy regional administration had previously announced.
In the small town of Myrnohrad in the Ukrainian-controlled part of the eastern Donetsk region, two people were killed and five injured in overnight shelling, the governor of the region, Vadym Filashkin, wrote on Telegram.
A 13-year-old girl was rescued from the rubble of the residential building unharmed. According to the governor, the attack was carried out by guided aerial bombs.
Russia launched a full-scale invasion of Ukraine more than two years ago and its forces regularly hit civilian targets beyond the front line.
Ukraine has also repeatedly attacked targets in Russia, though the number of victims and the extent of the damages are a far cry from the havoc wreaked by Moscow in over two years of war.