Ukrainian President Volodymyr Zelenskyy has accused Russian soldiers of committing war crimes and killing civilians in Kherson, parts of which were retaken by Ukraine's army last week after Russia pulled out.
"Investigators have already documented more than 400 Russian war crimes. Bodies of dead civilians and servicemen have been found," Mr Zelenskyy said in his nightly video address.
"The Russian army left behind the same savagery it did in other regions of the country it entered.
"We will find and bring to justice every murderer. Without a doubt."
Reuters was unable immediately to verify his allegations.
Russia denies its soldiers intentionally target civilians.
Mass graves have been found in a number of places across Ukraine since the start of the Russian invasion, including civilian bodies showing evidence of torture discovered in the Kharkiv region and in Bucha, near Kyiv.
Ukraine has accused Russian forces of committing the crimes.
A United Nations commission in October said war crimes were committed in Ukraine and that Russian forces were responsible for the "vast majority" of human rights violations in the early weeks of the war.
Fleeing Russians leave mines behind
Ukrainian forces arrived in the centre of southern Kherson region on Friday after Russia abandoned the only regional capital it had captured since Moscow launched its invasion in February.
The withdrawal marked the third major Russian retreat of the war and the first to involve yielding such a large occupied city in the face of a major Ukrainian counter-offensive that has retaken parts of the east and south.
Utility companies in Kherson region were working to restore critical infrastructure damaged and mined by fleeing Russian forces, with most homes in the southern Ukrainian city still without electricity and water, regional officials said.
About 70 per cent of the wider Kherson region is still in Russian hands.
On Sunday, artillery exchanges echoing over the city failed to discourage crowds of jubilant, flag-waving residents bundled up against the cold from gathering on Kherson's main square.
"We are happy now, but all of us are afraid of the bombing from the left bank," said Yana Smyrnova, 35, referring to Russian guns on the east side of the Dnipro River that runs close to the city.
Ms Smyrnova said she and her friends had to get water from the river for bathing and flushing their toilets, and only a few residents were lucky enough to have generators that power pumps to get water from wells.
The governor of Kherson region, Yaroslav Yanushevych, said the authorities had decided to maintain a curfew from 5pm to 8am and ban people from leaving or entering the city as a security measure.
"The enemy mined all critical infrastructure," Mr Yanushevych told Ukrainian TV.
"We are trying to meet within a few days and [then] open the city," he said.
Mr Zelenskyy also warned Kherson residents about the presence of Russian mines.
"I am asking you please not to forget that the situation in Kherson region remains very dangerous," he said.
He said one sapper had been killed and four others injured while clearing mines.
Local authorities said most of the city lacked electricity or water and food and medical supplies are short.
Yuriy Sobolevskiy, first deputy chairman of Kherson regional council, told Ukrainian TV that even as the authorities were working to restore critical services, the humanitarian situation remained "very difficult".
Trains to Kherson to resume soon
Officials have reported some early progress in restoring normality to the city.
Mr Zelenskyy's adviser Kyrylo Tymoshenko said a mobile phone internet connection was already working in the city centre, while the head of Ukrainian state railways said train services to Kherson were expected to resume this week.
Residents said the Russians had pulled out gradually over the past two weeks, but their final departure became clear only when the first Ukrainian troops entered Kherson on Thursday.
Many residents interviewed said they tried to minimise contact with the Russians and knew of people who were arrested and abused for showing any expression of Ukrainian patriotism.
Reuters could not immediately verify such accounts.
Russia has denied abuses against civilians or attacks on civilians since the war began.
Ukraine retakes villages and towns along crucial front
Ukraine's defence ministry said it had recaptured 179 settlements and 4,500 square kilometres (1,700 square miles) along the Dnipro River since the beginning of the week.
Ukrainian armed forces' general staff reported continued fierce fighting along the eastern front in the Donetsk and Luhansk regions.
During the past 24 hours, there have been missile and artillery strikes in Sumy, Kharkiv, Zaporizhzhia, Luhansk and Donetsk, Mr Zelenskyy said.
Reuters/AP/ABC
