In the report, OHCHR acknowledged that the actual number of civilian casualties is likely to be "considerably higher" due to the difficulty of obtaining reliable information from "some locations where intense hostilities have been going on."
The official figure of 4,031 civilian deaths includes 129 civilians killed in territory controlled by Russian-backed separatists in the Donbas.
These latest numbers come as Russia continues to press its attack in the Donbas. Luhansk Governor Sergiy Haidai said Saturday that the city of Sievierodonetsk is "not cut off," even as Russian troops continued to attack from three sides. Sievierodonetsk and its twin city, Lysychansk, represent one of the last pockets of Ukrainian resistance in Luhansk Oblast.
On Tuesday, Haidai told civilians trapped in Sievierodonetsk that there was no time left to evacuate.