Russia claimed to have breached two reinforced defence lines in eastern Ukraine, while Western allies vowed to increase military help to Kyiv in preparation for a counteroffensive.
As the first anniversary of its invasion approaches, it is widely anticipated that Russia will launch a big new push, bolstered by tens of thousands of reserve troops enlisted in December.
"The enemy's offensive continues in the east, (with) round-the-clock attacks," said Hanna Malyar, deputy minister of defence for Ukraine.
"The circumstance is tense. But our soldiers are preventing the enemy from achieving their objectives and suffering significant casualties, "Wednesday she said on the Telegram chat app.
Earlier, the Russian Defense Ministry said that Ukrainian forces had retreated in response to Russian operations in the Luhansk region. However, it did not provide any specifics, and Reuters could not independently verify this or other battlefield claims.
"During the offensive ... the Ukrainian troops randomly retreated to a distance of up to 3 km (2 miles) from the previously occupied lines," the ministry reported on Telegram.
"Even the more fortified second line of defence of the enemy could not hold the breakthrough of the Russian military."
The government did not disclose which section of Luhansk was affected by the offensive. The Luhansk and Donetsk regions comprise the Donbas, the industrial core of Ukraine, which is currently partially occupied by Russia and seeks total control.
The military administration of Kyiv reported that six Russian reconnaissance balloons were shot down following the sounding of air raid sirens.
The Telegram messaging service stated that the goal of launching the balloons was possible to detect and exhaust our air defences. Russia did not comment immediately.
Russia's primary endeavour has been an artillery and ground assault on the Donetsk city of Bakhmut.
Oleh Zhdanov, a Ukrainian military analyst, reported that Russian soldiers had attacked many settlements, notably Paraskoviivka, on the northern approaches to Bakhmut in the past day.
He stated in a YouTube video that Russian attempts to advance on two more communities north of Bakhmut were rebuffed.
Zhdanov stated, "Things are complicated for our forces there as Russian troops are being sent into the area en masse,"
Maksym Zhorin, a military analyst and former commander, told Ukrainian Radio NV that the Russians were attacking the southern entrances to Bakhmut, Opytne and Klishchiivka.
He claimed that there was also significant fighting in Krasna Hora, north of Bakhmut, where Ukrainians incurred casualties.
"The injured can be removed, and the city can be supplied. We can continue our defence for very some time, "he remarked.
In its evening report, the General Staff of the Ukrainian Armed Forces stated that Russian forces had opened fire on more than 15 towns and villages in the vicinity of Bakhmut, including the city itself.
Pavlo Kyrylenko, the regional governor of Donetsk, released photographs and a video of a demolished apartment complex in Pokrovsk, southwest of Bakhmut, where three people were killed.
The conquest of Bakhmut would provide Russia with a stepping stone to push on two larger cities, Kramatorsk and Slovyansk, further west in Donetsk, reviving Moscow's momentum before the invasion's anniversary on February 24.
According to the alliance, NATO nations are increasing the production of artillery munitions because Ukraine is consuming shells faster than its allies can produce them.
NATO leader Jens Stoltenberg told reporters following a two-day conference of alliance defence ministers in Brussels, "Things are happening, but ... we need to step up even more because there is a big need out there to provide Ukraine with ammunition,"
The United States has provided around $27.4 billion in security assistance to Ukraine since the beginning of the conflict.
European Union foreign policy leader Josep Borrell encouraged nations to send tanks alongside Germany.
Through an international fund, Britain and other European nations will supply military equipment, including tank spare parts and artillery ammunition, with an initial package valued at more than $241 million.
This year, according to U.S. Defense Secretary Lloyd Austin, Ukraine has an excellent opportunity of seizing and "exploiting" the initiative on the battlefield.
Russia refers to the invasion as a "special military operation" against security concerns and the delivery of heavy weaponry to Ukraine as evidence that the West is intensifying the conflict.
Kyiv and its allies refer to Russia's actions as an annexation.
Senior U.S. officials instructed Ukraine not to launch a significant offensive until the most recent shipment of U.S. weapons was in place, and training was supplied.
Ukraine's President Volodymyr Zelenskiy stated in an evening address, "We have to ensure that this spring it is truly felt that Ukraine is moving towards victory,"