"Unsanitary conditions are growing" in Severodonetsk and "there is not enough water and not enough food" in the city, said Roman Vlasenko, head of the eastern city's regional administration.
There are also issues with gas and electricity supplies, Vlasenko added.
Severodonetsk fell to Russian forces in June following months of grueling and bloody fighting, leaving the Luhansk region almost fully under Russian control.
He described the living situation as “very sad” for those that have remained even though "there are not many people left there."
A sign in the city was repainted from Ukrainian to Russian colors on Monday.
Vlasenko said "pressure continues on pro-Ukrainian activists" and they continue to face serious challenges.