Moscow-installed officials have said Ukrainian shelling killed at least 27 people and wounded 25 at a market on the outskirts of Donetsk, a Russian-occupied city in the eastern part of the country.
Among the injured in the suburb of Tekstilshchik were two children, said Denis Pushilin, the local leader.
Ukrainian officials in Kyiv did not comment on the incident, and the claims could not be independently verified by The Associated Press.
Both sides have increasingly relied on longer-range attacks this winter amid largely unchanged positions on the 1,500-kilometre (930-mile) front line in the nearly two-year-old war.
The artillery shells that hit the area had been fired from the area of Kurakhove and Krasnohorivka to the west, Mr Pushilin said, adding that emergency services responded to the scene.
UN secretary-general Antonio Guterres “strongly condemns all attacks against civilians and civilian infrastructure, including today’s shelling of the city of Donetsk in Ukraine”, according to a UN spokesperson, adding that all such attacks are prohibited under international humanitarian law.
Donetsk is one of four regions in Ukraine that Russia annexed illegally in 2022, months after Moscow launched its full-scale invasion.
Russia’s Foreign Ministry also blamed Ukraine and described the strike as a “terrorist attack”.
Also on Sunday, a fire broke out at a chemical transport terminal at Russia’s Ust-Luga port following two explosions, regional officials said.
Local media reported the port had been attacked by Ukrainian drones, causing a gas tank to explode.
The blaze was at a site run by Russia’s second-largest natural gas producer, Novatek, 100 miles south-west of St Petersburg.
In a press statement to Russian media outlet RBC, the company said the fire was the result of an “external influence”. It also said it had paused operations at the port.
Yuriy Zapalatskiy, the head of Russia’s Kingisepp district where the port is based, said in a statement there were no casualties, but the district has been placed on high alert.
News outlet Fontanka reported two drones had been detected flying towards St Petersburg on Sunday morning, but they were redirected towards the Kingisepp area.
The Russian Ministry of Defence did not report any drone activity in the Kingisepp area in its daily briefing. It said four Ukrainian drones had been downed in Russia’s Smolensk region, and two more had been shot down in the Oryol and Tula regions.
Russian officials previously confirmed a Ukrainian drone had been downed on the outskirts of St Petersburg on Thursday.