"We ask international partners, especially the African Union and regional partners, to work with us to address the crisis in Tigray, including through action at the UN and other relevant bodies," US Secretary of State Antony Blinken said.
The US has condemned alleged atrocities committed in Ethiopia's Tigray and called on the African Union and other international partners to help address the crisis in the conflict-hit region.
The comments by US Secretary of StateAntony Blinken on Saturday came a day after a report by Amnesty International alleging Eritrean soldiers fighting in Tigray had killed hundreds of people in November last year in what the rights group described as a likely crime against humanity.
"The United States is gravely concerned by reported atrocities and the overall deteriorating situation in the Tigray region of Ethiopia," Blinken said in a statement.
"We are also deeply concerned by the worsening humanitarian crisis."
Tigray has been the theater of fighting since early November, when Ethiopian Prime Minister Abiy Ahmed announced military operations against the northern region's former ruling party, the Tigray People's Liberation Front, accusing it of attacking federal army camps.
Pro-government troops took the regional capital Mekele in late November but clashes have persisted in the region.
"We ask international partners, especially the African Union and regional partners, to work with us to address the crisis in Tigray, including through action at the UN and other relevant bodies," Blinken said.
He called for the "immediate withdrawal" of Eritrean forces and Amhara regional forces from Tigray and unilateral declarations of a cessation of hostilities by all parties.
The presence of Eritrean troops in Ethiopia in the Tigray conflict has been widely documented but has been denied by both countries.
Eritrea has rejected Amnesty's allegations.
Blinken in early February had voiced grave concern over Tigray and urged immediate humanitarian access.