GENEVA — The United Nations said on Thursday that 236 civilians were killed in conflict-related violence in Ukraine in the 12-month period to mid-February, and it estimated that at least 9,160 had died since the conflict started in April 2014.

The number of casualties from fighting between government forces and pro-Russian armed groups in eastern Ukraine has fallen in recent months, Gianni Magazzeni, a senior official at the Office of the High Commissioner for Human Rights, said in Geneva, but rights monitors have continued to receive reports of killings, abductions, torture and poor treatment of prisoners by rebel groups.

“Since we have no access, the worst is to be expected,” Mr. Magazzeni said.

United Nations monitors have also received reports of enforced disappearances and torture by Ukraine’s security services, he said.