Russia has shelled more than 100 settlements over the last 24 hours - more than in any single day so far this year, Ukraine said on Wednesday.
"Over the last 24 hours, the enemy shelled 118 settlements in 10 regions," Ukrainian Interior Minister Igor Klymenko said on social media.
"This is the highest number of cities and villages that have come under attack since the start of the year," he added.
Kyiv also reported a Russian attack on an oil refinery in Kremenchuk, a central industrial city.
There were no casualties but it took almost 100 firefighters several hours to put out the resulting blaze, Klymenko said.
Kyiv and the West fear Russia will escalate its attacks on Ukraine's energy infrastructure ahead of the cold winter - as it did last year.
The overnight shelling in the northeastern Kharkiv region killed one person, and another was killed in the southern Kherson region, local officials said.
During the day, Ukraine said a Russian drone attack on the southern city of Nikopol killed a 59-year-old woman and injured four others. A rocket strike on a village in the Zaporizhzhia region killed a 52-year-old man.
Both Kyiv and Moscow said they had also shot down enemy drones overnight.
Since the start of the war, Russia has dramatically ramped up its domestic arms production while also tapping its few foreign partners for ammunition supplies.
Citing intelligence information, a South Korean lawmaker said Wednesday that North Korea has provided Russia with over one million artillery rounds.
Western countries have meanwhile provided billions of dollars of military aid to Kyiv to help defend against Russian attacks.
Zelensky warns allies not to expect 'instant success' against Russia
Meanwhile, Ukraine's President Volodymyr Zelensky said that attacks on the Russian Navy in the Black Sea have crippled Moscow's war efforts as he sought to rally his troops even as the outside world expects instant successes.
Despite Ukraine's gruelling months-long offensive, the vast frontline in Ukraine's east and south has moved little in the past year, spurring criticism and impatience among some of Ukraine's Western allies.
"We live in a world that gets used to success too quickly. When the full-scale invasion began, many people around the world did not believe that Ukraine would survive," Mr Zelensky said in his nightly video address.
"Glory to all those who do not retreat, who do not burn out, who believe in Ukraine just as they did on 24 February, and who has been fighting for unwaveringly."
The war, which Russia launched on 24 February, 2022, is now in its 20th month and has no end in sight. Russian forces have geared up for fresh attacks in different sections of the front and are suffering heavy losses.
Mr Zelensky said his troops have succeeded in diminishing Moscow's military strength in the Black Sea, which he said with greater support from Kyiv's allies could lead to Ukraine's ultimate victory over Russia.
The Black Sea has become a crucial theatre in the war. Ukraine's increased air and sea drone attacks on Russian military targets there have damaged ship and naval repair yards in the port of Sevastopol, and struck other targets.
Russia uses its fleet in the Black Sea to launch long-range strikes on Ukraine. But for President Vladimir Putin, the waters - which connect to the Mediterranean Sea - are also an important springboard for projecting power into the Middle East, Europe and the West.
"When we ensure even more security to the Black Sea, Russia will lose any ability to dominate in this area and expand its malign influence to other countries," Mr Zelensky said.
The full extent of the damage that Ukraine has done in recent months to the Russian Black Sea Fleet remains unclear. The Russian defence ministry's statements mostly claim success in destroying the weapons, with little evidence.
"Ukraine's success in the battle for the Black Sea will go down in history books, although it's not being discussed much today," Mr Zelensky said.
Struggle at the frontline
At the frontline, however, there has been a struggle.
Mr Zelensky said a meeting with senior commanders had considered sectors engulfed by the fiercest fighting in the east and northeast, including the key areas of Avdiivka and Kupiansk, where Russia has been on the offensive in recent weeks.
Vitaly Barabash, head of the military administration in Avdiivka, said the shattered eastern city was bracing for a new wave of the attacks it had been withstanding since mid-October.
"The enemy is bringing in forces and equipment. Our boys are preparing for a new wave," Mr Barabash told national television.
Avdiivka, with its vast coking plant, was briefly captured in 2014 when Russian-backed separatists seized chunks of land in the east, but Ukrainian forces have since put up fortifications.
Ukraine's ground forces said yesterday that Russian forces were also focused on Kupiansk - a city in the northeast overrun by Russia in the early days of the invasion, but recaptured by Ukrainian forces last year.
Russia's accounts of the fighting said its forces had conducted successful attacks near the town of Bakhmut - a largely destroyed town captured by Russian forces in May.
Reuters could not verify accounts of fighting from either side.
