Russian forces, focused for weeks on seizing the key eastern Ukrainian town of Avdiivka, are now intent on capturing its vast coking plant, the town's mayor said on Friday.
Ukrainian military officials said a heavy overnight set of drone strikes on widely separated regions showed new attacks on infrastructure were to be expected as winter approaches.
Russia's military has focused on the eastern regions of Donetsk and Luhansk after abandoning the initial aim of capturing Kyiv in the early days of the February 2022 invasion.
Russian forces captured the devastated town of Bakhmut in May after months of battles and since mid-October have focused their assaults on Avdiivka, a potential gateway to Donetsk, held by Russian forces and their allies since 2014.
Ukraine's General Staff, in a Friday evening report, said its forces had repelled 17 attacks on and around Avdiivka.
Mayor Vitaliy Barabash, speaking on national television, said audio transmission intercepts had revealed that Moscow was now seeking to secure the town's giant coking plant.
"They have a new aim and that's the coking plant. They have to take it. Period," Barabash said.
"We understand that a (new) third wave of attacks is bound to start any day once the ground dries out and they can move forward. They are engaged in a build-up. We see and hear that."
Ukrainian military analysts say a sustained assault on Avdiivka had more political that military significance and could be little more than a propaganda prize for Moscow.
The General Staff report also reported that Ukrainian forces had repelled seven attacks near Kupiansk, a town in the northeast first seized by Russia but recaptured by Ukrainian forces in a fast-moving offensive late last year.
Natalia Homeniuk, a spokesperson for the southern group of forces, said Russia's Friday overnight attacks "used a large number of drones for the first time in a long while".
"Most likely, the enemy will launch more drones and missiles as the cold weather sets in," Homeniuk told a briefing.
The Ukrainian air force said it shot down 24 "Shahed" drones out of 40 launched by Russia against targets in Kharkiv in the northeast, Odesa and Kherson in the south and the region of Lviv on Ukraine's border with Poland in the west.
Ukraine has captured villages in the south and east in its four-month-old counteroffensive, but President Volodymyr Zelensky denies Western criticism that it has moved too slowly.
Russian accounts of the fighting said Moscow's forces beat back Ukrainian attempts to advance near Kupiansk and struck Ukrainian forces in a series of towns south and west of Donetsk.
Reuters could not verify accounts from either side.