President Volodymyr Zelenskiy urged vigilance ahead of Wednesday's celebrations of 31 years of Ukraine's independence from Soviet rule, as shells rained down near Europe's biggest nuclear plant and Russian forces struck in the south and east.
Ukrainians must not allow Moscow to "spread despondency and fear" ahead of the Aug. 24 events, which also mark six months since Russia began its full-scale invasion of Ukraine, Zelenskiy said in his nightly video address on Saturday.
"We must all be aware that this week Russia could try to do something particularly ugly, something particularly vicious," Zelenskiy said.
In Russia, the daughter of an ultra-nationalist Russian ideologue who advocates Russia absorbing Ukraine was killed in a suspected car bomb attack outside Moscow on Saturday evening, Russian state investigators said on Sunday.
They said Darya Dugina, daughter of prominent ideologue Alexander Dugin, was killed after a suspected explosive device detonated on the Toyota Land Cruiser she was travelling in, and they were considering "all versions" when it came to working out who was responsible.
The nightly curfew in Ukraine's second-largest city, Kharkiv, regularly hit by Russian shelling, will be extended for the entire day on Wednesday, regional Governor Oleh Synehub told residents on the Telegram messaging app.
As the war that has killed thousands and forced millions to flee heads for its half-year mark, Ukrainian military and local officials reported more Russian strikes overnight on targets in the east and south of the country.
Ukraine's general staff said on Facebook early on Sunday that over the past 24 hours Russian forces had conducted several attempted assaults in Donbas. The eastern border region controlled in part by pro-Moscow separatists has been a prime target of Russia's campaign in the past months.
In the south, Russian forces conducted a successful assault on a village of Blahodatne at the border between Kherson and Mykolaiv regions. The city of Mykolaiv was hit with multiple S-300 missiles early on Sunday, regional governor Vitaliy Kim said on Telegram.
The area on the Black Sea coast has seen some of the fiercest fighting of the past weeks.
To the northeast, the city of Nikopol, which lies across the Dnipro river from Zaporizhzhia, Europe's biggest nuclear plant, was shelled on five different occasions overnight, regional governor Valentyn Reznichenko wrote on Telegram. He said 25 artillery shells hit the city, causing a fire at an industrial premises and cutting power to 3,000 residents.
The fighting near the Russian-controlled plant and Saturday's missile strike at the southern Ukrainian town of Voznesensk, not far from the country's second-largest nuclear plant, revived fears of a nuclear accident.
The attack on Voznesensk was "another act of Russian nuclear terrorism", state-run Energoatom, which manages Ukraine's four nuclear energy generators, said in a statement.
Russia did not immediately respond to the accusation. Reuters could not verify the situation in Voznesensk. There were no reports of damage to the power plant.
As Moscow and Ukraine continue to trade accusations of shelling around the Zaporizhzhia complex, the United Nations has called for a demilitarized zone around the plant and talks continued about a visit of its nuclear agency to the area.
Zelenskiy in his speech also referred obliquely to a recent series of explosions in Crimea, the Black Sea peninsula Russia annexed from Ukraine in 2014.
Ukraine has not claimed responsibility for the attacks, but analysts have said at least some have been made possible by new equipment used by its forces.
"You can literally feel Crimea in the air this year, that the occupation there is only temporary and that Ukraine is coming back," Zelenskiy said.
In the latest incident, Crimea's Russian-appointed governor, who is not recognised by the West, said a drone attack on the headquarters of Russia's Black Sea fleet was thwarted on Saturday morning.
"It was downed right over the fleet headquarters. It fell on the roof and burned up. The attack failed," Mikhail Razvozhayev said on Telegram.
Razvozhayev said the region's anti-aircraft system had again been in operation and asked residents to stop filming and disseminating pictures of how it was working.
Ukrainian media reported explosions in nearby towns, among them the resorts of Yevpatoriya, Olenivka and Zaozyornoye.
Further west, five Kalibr missiles were fired from the Black Sea at the Odesa region overnight, according to the regional administration, citing the she southern military command. Two were shot down by Ukrainian air defences while three hit grain storage, but there were no casualties.
Odesa and other ports in the region have been at the centre of an U.N.-brokered deal to allow Ukrainian grain exports, blocked by the war, to reach world markets again. On Sunday, Turkey's defence ministry reported four more food-laden ships left Ukrainian ports, bringing the total to 31.