Ukraine's general staff has rejected Russian claims that Moscow's forces had captured the key eastern city of Kostiantynivka.
"We deny this. These are more fake claims," a general staff official said on Saturday.
The General Staff said Kostiantynivka remained under the control of Ukrainian forces.
"Military units and subunits of the 19th Army Corps of the Eastern Grouping continue to conduct defensive operations on designated lines within the town and on its approaches," it said.
Russia's military told President Vladimir Putin on Friday that its forces had taken control of Kostiantynivka, a strategic target that Moscow has long sought in its advance through the Donetsk region.
Kostiantynivka is the southernmost of four key settlements that form a defensive line central to Ukraine's effort to hold the heavily industrialised Donetsk region.
Analysts say capturing Kostiantynivka would give Russian forces a foothold from which to push north along the defensive belt, now the main axis of their campaign.
Russia's military has for some time reported controlling parts of Kostiantynivka, one of several heavily fortified cities that make up Ukraine's so-called "fortress belt" in Donetsk.
Ukrainian drone hit oil terminal in St Petersburg
Meanwhile, Ukraine attacked an oil terminal at the Port of St Petersburg overnight, Russian officials said on Saturday.
St Petersburg Gov Aleksandr Beglov said the city came under a large-scale Ukrainian drone attack and that air defences shot down 72 drones. One drone crashed in the Peterhof area.
"The strike hit an oil terminal in the city's Kirovsky District. The aftermath has been cleared. There were no casualties," Beglov said.
Local Telegram channels earlier reported a fire at the port's oil terminal following the overnight attack.
Separately, Russia's defence ministry said on Telegram that its air defences intercepted or destroyed 389 Ukrainian drones over several Russian regions, Crimea, annexed by Moscow in 2014, and the Azov and Black seas.
Ukraine's military hit oil and military facilities near Russia's St Petersburg overnight, Ukrainian President Volodymyr Zelenskyy confirmed on Saturday.
"Ukraine's defence forces struck port oil infrastructure that generates revenue for Russia's war, and also hit Kronstadt, an important military target more than 850 km (528 miles) from Ukraine's state border," he said on Telegram.
Russia hits gas production facility in Ukraine
On the other hand, Russia on Saturday struck a gas production facility with a drone in Ukraine's central Poltava region, causing a fire, Ukrainian state energy firm Naftogaz said.
"A fire broke out at the site after the attack. Operations at the facility have been suspended," Naftogaz said on Telegram.
"The enemy is systematically targeting gas production facilities in an attempt to reduce Ukraine's domestic output and complicate preparations for the heating season," it added.
