Russian forces have intercepted a Ukrainian drone near the Russian town of Kurchatov but there was no damage to the nearby Kursk nuclear power plant, the regional governor says.
Governor Alexei Smirnov said debris from the drone caused explosions in a building unrelated to the plant.
Several Russian Telegram channels earlier reported the alleged Ukrainian attack, which they said had been thwarted by air defences but had resulted in a fire several kilometres from the nuclear plant.
The plant's operator, Rosenergoatom, said the facility was operating as usual and radiation levels remained within normal limits.
In a post on X, Ukrainian Foreign Ministry spokesman Heorhiy Tykhyi denied that Ukraine had fired weapons at or near the plant.
Reuters could not independently confirm the reports.
Ukrainian forces entered the Kursk region in a surprise cross-border incursion on August 6 and remain there even as the Russian military tries to eject them.
Rafael Grossi, head of the United Nations nuclear watchdog, visited the nuclear plant on August 27 and said it was especially vulnerable to a serious accident because it lacks a protective dome that could shield it from missiles, drones or artillery.
Ukrainian police said a Russian drone targeted a truck delivering gas in a border district of Ukraine's northern Chernihiv region on Thursday, killing two adults and a child.
"The Russians deliberately hit a truck delivering liquefied gas to people with a drone. The gas cylinders detonated. Residential buildings caught fire," regional governor Vyacheslav Chaus said on Telegram.
A six-year-old child was among the victims, he added.
A four-year-old boy and a 13-year-old girl were among four wounded people hospitalised after the attack, Chaus said.
Both of them were in severe condition, he added.
Images from the site he posted alongside showed a truck completely burnt out and flames raging near private houses.
Ukrainian drones attacked the "Borisoglebsk" military airfield and warehouses for fuel and guided bombs in Russia's Voronezh region overnight, a Ukrainian security source told Reuters.
The security source said Ukraine's SBU security service was continuing actions to reduce the ability of Russian troops to use fighter jets with guided bombs to strike Ukrainian cities, and that attacks on Russian airfields would continue.
The drones attacked warehouses, parking lots for Russian Sukhoi Su-35 and Su-34 jets and aviation fuel storage facilities at the Borisoglebsk airfield, the source said.
"From there, the enemy actively bombards Ukrainian territories with guided bombs," the source said, sharing pictures and a short video clip showing fires.
Reuters could not independently verify the assertions or the images.
The extent of the damage was not immediately clear.
Alexander Gusev, the governor of Russia's Voronezh region, said on Telegram that Russian air defence had shot down 10 drones over the region.
He did not report any damage.
Russia, which began its full-scale invasion in February 2022, has intensified the use of guided bombs in attacks on Kharkiv and Sumy in northeastern Ukraine and on Zaporizhzhia in the southeast, and use guided bombs along front lines.
Ukrainian President Volodymyr Zelenskiy said last month that Russia was using "hundreds of guided bombs' each day.