Russia shelled more than 40 towns in the region, destroying nearly a dozen high-rise buildings, authorities said. Moscow's forces sought to surround their Ukrainian foes, outnumbering them in some places.
Russia has poured thousands of troops into the region, attacking from three sides in an attempt to encircle Ukrainian forces holding out in the city of Sievierodonetsk and its twin Lysychansk. Their fall would leave the whole of Luhansk province under Russian control, a pivotal Kremlin goal.
"The occupiers shelled more than 40 towns in Donetsk and Luhansk region, destroying or damaging 47 civilian sites, including 38 homes and a school. As a result of this shelling, five civilians died and 12 were wounded," the Joint Task Force of Ukraine's armed forces said on Facebook.
The statement said 10 enemy attacks were repelled, four tanks and four drones destroyed, and 62 "enemy soldiers" were killed.
Ukraine's Deputy Defence Minister Ganna Malyar told a press briefing: "The fighting has reached its maximum intensity.
"Enemy forces are storming the positions of our troops simultaneously in several directions. We have an extremely difficult and long stage of fighting ahead of us," she added.
Ukraine President Volodymyr Zelenskyy's office said 11 high-rise buildings were destroyed.
Mr Zelenskyy has said Russian troops heavily outnumber Ukrainian forces in some parts of the east and Kyiv has been trying unsuccessfully to arrange a prisoner swap with Moscow.
Those “great geopoliticians” who suggest this are disregarding the interests of ordinary Ukrainians — “the millions of those who actually live on the territory that they propose exchanging for an illusion of peace", he said in his nightly video address to the nation. He was referring to comments made at the World Economic Forum in Davos by the former Henry Kissinger, the former US Secretary of State, who said Ukraine should be willing to cede some territory in pursuit of peace.
“We always have to think of the people and remember that values are not just words."
In an Instagram post accompanying the message, Mr Zelenskyy said: “No matter what the Russian state does, there is always someone who says: 'Let's take its interests into account.'
"This year in Davos it was heard again, despite thousands of Russian missiles hitting Ukraine, despite tens of thousands of Ukrainians killed, despite Bucha and Mariupol, et cetera. Despite the destroyed cities.
"And despite the 'filtration camps' built by the Russian state, in which they kill, torture, rape and humiliate like on a conveyor belt. Russia has done all this in Europe.
"But still in Davos, for example, Mr Kissinger emerges from the deep past and says that a piece of Ukraine should be given to Russia, so that there is no alienation of Russia from Europe.”
Meanwhile, Moscow pressed the West on Thursday to lift sanctions against Russia over the war. The Kremlin is seeking to shift the blame for a growing food crisis, worsened by Kyiv’s inability to ship millions of tonnes of grain and other agricultural products, because of the conflict.
Ukraine is one of the world’s largest exporters of wheat, corn and sunflower oil. However, the war, including a Russian blockade of its ports, has prevented much of that production from leaving the country, endangering the world food supply. Many of those ports are also now heavily mined.
Kremlin spokesman Dmitry Peskov tried to put the blame for the crisis squarely on Western sanctions.
“We accuse Western countries of taking a series of unlawful actions that has led to the blockade,” he said in a conference call with reporters.
Russia itself is also a significant exporter of grain, and Mr Peskov said the West “must cancel the unlawful decisions that hamper chartering ships and exporting grain.”
British Foreign Secretary Liz Truss said on Thursday that Russian President Vladimir Putin was “trying to hold the world to ransom” by demanding that some sanctions be lifted before allowing Ukrainian grain shipments to resume.