The US has called for the release of thousands of ethnic Tigrayans who reportedly remain detained arbitrarily in Ethiopia, and wants access to be granted to international monitors.
A joint report by rights groups Amnesty International and Human Rights Watch had earlier accused Amhara forces of waging a campaign of ethnic cleansing against ethnic Tigrayans in disputed areas.
The two rights groups also claimed that the federal government have approved or possibly participated in the alleged atrocities.
The US expressed concern over what it called ethnically-motivated atrocities against Tigrayans in western Tigray.
Ethiopia has called the humanitarian report unhelpful but pledged to examine the allegations.