Russia is concentrating its forces near the Ukrainian city of Siversk and will attempt to take the surrounding area in the coming days, Britain's defence ministry has said.
In an updated intelligence briefing, the Ministry of Defence said Russian forces were likely pausing to replenish before undertaking new offensive operations in the eastern Donetsk region.
Russia's immediate tactical objective might be Siversk, a small industrial city in the north of Donetsk, it said. The city is about 8km west of the current Russian front line.
However, the briefing said Ukrainian forces were continuing to make gradual advances in the south-western Kherson sector which was initially taken by Russian forces in the early stages of the war.
After failing to take the capital Kyiv, Russia is now waging a war of attrition in Ukraine's industrial heartland of the Donbas, made up of the regions of Luhansk and Donetsk.
Moscow declared it had "liberated" Luhansk and now plans to capture parts of neighbouring Donetsk it does not control.
Luhansk governor Serhiy Gaidai on Friday said Russian forces were shelling villages, towns and cities indiscriminately.
"They are not stopped even by the fact that civilians remain there, dying in houses and yards. They hit houses, every building that seems to them a possible fortification," he said.
The situation was similar in settlements in Donetsk.
Vadym Lyakh, the mayor of Sloviansk, said a woman was killed overnight when Russian shelling hit a residential building.
A Ukrainian official on Friday issued a warning of deteriorating living conditions in the captured city of Severodonetsk which is without water, power or a working sewage system.
Mr Gaidai said the Russians were unleashing indiscriminate artillery barrages as they try to secure their gains in Luhansk.
“Luhansk hasn’t been fully captured, even though the Russians have engaged all their arsenal to achieve that goal,” Mr Gaidai told The Associated Press. “Fierce battles are going on in several villages on the region’s border. The Russians are relying on tanks and artillery to advance, leaving scorched earth.”
Russia’s forces “strike every building that they think could be a fortified position”, he said. “They aren’t stopped by the fact that civilians are left there and they die in their homes and courtyards. They keep firing.”
Occupied Severodonetsk, meanwhile, “is on the verge of a humanitarian catastrophe”, the governor wrote on social media. “The Russians have completely destroyed all the critical infrastructure, and they are unable to repair anything.”
Mr Gaidai had said about 8,000 residents remained in the city, which had a pre-war population of around 100,000.
Donbas is a region of mines and factories where pro-Moscow separatists have fought Ukraine’s army for eight years and declared independent republics that Russian President Vladimir Putin recognised before he sent troops into Ukraine in February.
In a post on Telegram messaging app, Ukrainian President Volodymr Zelenskyy said he visited troops along the Dnipropetrovsk front line in central Ukraine.
He said on Friday: "Spoke with our defenders, presented them with awards. Their mood is determined, in their eyes — confidence in our victory. Thank you for fighting for the freedom of Ukraine!"