In its latest report, the Ethiopian Human Rights Commission underscores the need to put an urgent stop to the continued suffering caused to civilians in the conflict.
Tigrayan rebels have killed scores of civilians in the Amhara region on suspicion of being informants or offering aid to federal Ethiopian forces.
Ethiopian Human Rights Commission, in its report published on Saturday, accused Tigray People's Liberation Front (TPLF) fighters of "willfully" killing at least 184 civilians in towns and rural areas captured by them.
Civilians were shot and killed for supporting the federal government or for sheltering wounded soldiers, the commission said.
"TPLF forces shot and killed mentally ill residents of towns they controlled on suspicion of being informants for the government," it added.
Local youth, meanwhile, killed people who had fled war-torn Tigray, accusing them of spying for the TPLF, it said.
"Additionally, both warring sides engaged in indiscriminate shelling that was not directed at a specific military objective causing civilian deaths, injuries and damage to civilian property."
The investigation, which draws on 128 interviews, focuses on parts of Amhara which saw heavy fighting in July and August as the country's brutal conflict enters its second year.
EHRC Chief Commissioner Daniel Bekele said that violations and abuses were committed by all parties in South Gondar and North Wollo Zones of the Amhara region.
Prime Minister Abiy Ahmed's government has said it is committed to holding perpetrators of abuses accountable.
Ethiopia, Eritrea condemn US sanctions
Ethiopia and Eritrea, meanwhile, have denounced new US sanctions on Asmara over its alleged role in the deadly conflict, calling on Washington to "rescind its decision".
"The real target for sanctions and further tougher actions by the US government and the greater international community should be directed towards the TPLF," Ethiopia's Foreign Ministry said on Saturday.
On the other hand, Eritrea called the move "illicit and immoral".
"This unilateral sanction, that shifts blame to and scapegoats Eritrea on the basis of spurious allegations, is in contravention of international law, and constitutes a flagrant breach of ... sovereignty," the country's Ministry of Information said in a statement.
"That the primary aim of the illicit and immoral sanctions is to inculcate suffering and starvation on the population so as to induce political unrest and instability is patently clear."