Ukraine's Kremenchug oil refinery has been completely destroyed after a Russian attack, Dmytro Lunin, governor of the Poltava region, said on television on Sunday.
"The fire at the refinery has been extinguished but the facility has been completely destroyed and can no longer function," Mr Lunin said.
Earlier, officials in Odesa said Russia missiles had struck "critical infrastructure" near Ukraine's southern port city in the early hours of Sunday but there were no casualties.
At least three huge columns of black smoke and flames rose into the sky over an industrial zone.
Odesa, a historic city of around one million people on the Black Sea coast, is a key port and the main base for Ukraine's navy. It has been a focus for Russian forces because if it is taken it would allow Moscow to build a land corridor to Transdniestria, a Russian-speaking breakaway province of Moldova that hosts Russian troops.
Smoke and fire are seen after the shelling of "critical infrastructure" in Odesa, Ukraine. Source: AAP / Max Pshybyshevsky/AP
"This morning, high-precision sea and air-based missiles destroyed an oil refinery and three storage facilities for fuel and lubricants near the city of Odesa, from which fuel was supplied to a group of Ukrainian troops in the direction of Mykolaiv," it said.
The rocket attacks came as Russian forces appeared to be withdrawing from the country's north after Kyiv warned that Moscow was trying to consolidate troops in the south.
Despite the rocket attacks,there were no casualties, said officer Vladislav Nazarov in a statement from the southern regional command that reiterated a ban on publishing the exact sites under fire or the extent of damage.
"Russia began with a missile strike. The Odesa region was among the priority targets. The enemy continued its vile practice of strikes against critical infrastructure," he said.
"Smoke is visible in some areas of the city. All relevant systems and structures are working ... No casualties reported."
Vika, a local resident who declined to give her surname, said it was not "a good morning for Odesa".
"We woke up to powerful explosions near our home. There was smoke, the children were in a panic, the windows were blown in ... it was terrifying," she told Reuters.
"'Russian peace', we are completely not happy that it has come and we ask you to leave."
On Friday, Ukraine's President Volodymyr Zelenskyy warned Russia was consolidating and preparing "powerful strikes" in the south, joining a chorus of Western assessments that Moscow's troops were regrouping.
Ukraine's whole eastern flank from Crimea, which Russia seized in 2014, to the pro-Moscow enclaves of Donetsk and Lugansk in the Donbas region is occupied by Russian forces, with the exception of the besieged city of Mariupol.
The assault on Odesa comes as Ukraine said its forces had and the mayor of a liberated town said 300 residents had been killed during a month-long occupation by the Russian army, and .
Ukrainian troops have retaken more than 30 towns and villages around Kyiv, Ukrainian officials said on Saturday, claiming complete control of the capital region for the first time since Russia launched its invasion on 24 February.
Russia has labelled the invasion a "special military operation" to demilitarise and "denazify" its neighbour.
Ukraine rejects that as a baseless pretext for a war of aggression.
