Extensive destruction has left the population of Chernihiv without water, heating or electricity as Russian troops continue to surround the northern Ukrainian city.
Gas supplies were still partly functional, according to the regional administration on Sunday.
The city's infrastructure had been destroyed by "active fighting" but efforts are under way to repair the damage, administration chief Viacheslav Chaus wrote on Telegram.
Russian troops have surrounded the northern city for some time.
A key road from the city, located near the Russian and Belarusian borders, leads to Kyiv.
Mayor Vladyslav Atroshenko said the city was "completely devastated" by Russian troops, in comments on Saturday.
He said more than 200 civilians have been killed in recent weeks and that more than half of the city's original 285,000 residents had left.
The figures could not be independently verified.
Fighting continued throughout the country, with Russian forces also firing on the Neutron Source nuclear research facility in the eastern city of Kharkiv, according to Ukrainian media reports.
The facility was shelled on Saturday, Ukrayinska Pravda reported, citing the state nuclear watchdog.
"Verification of the extent of the damage is impossible due to the uninterrupted fighting in the vicinity of the nuclear facility," the report said.
The facility had already been damaged in a bombing nearly two weeks ago and cut off from its power supply.
While the facility is listed in the International Atomic Energy Agency's (IAEA) database of research reactors, it is not a classic reactor, according to GRS, a German nuclear safety watchdog.
The IAEA had previously said that nuclear chain reactions are not taking place at the facility and that only very small quantities of radioactive material are stored there.
Australian Associated Press
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