JOHANNESBURG — The United States is “gravely concerned by reported atrocities and the overall deteriorating situation” in Ethiopia’s Tigray region, U.S. Secretary of State Antony Blinken said in the toughest statement yet from Washington on Ethiopia’s ongoing conflict.

Accounts of atrocities by Ethiopian and allied forces against residents of the country’s northern region of Tigray were detailed in reports by The Associated Press and by Amnesty International. Ethiopia’s central government and regional officials in Tigray both believe that each other’s governments are illegitimate after the pandemic disrupted elections.

“We strongly condemn the killings, forced removals and displacements, sexual assaults, and other extremely serious human rights violations and abuses by several parties that multiple organizations have reported in Tigray. We are also deeply concerned by the worsening humanitarian crisis,” said Blinken in a statement issued Saturday.

Those responsible for abuses in Tigray must be held accountable, Blinken added, calling for an independent, international investigation into the reports of human rights violations.

The U.S. urged the immediate withdrawal from Tigray of troops from the neighboring country of Eritrea and from Amhara, the Ethiopian region bordering Tigray. It also called for the Ethiopian government to cease all hostilities in Tigray and to allow “unhindered delivery of assistance to those in Tigray.”

USAID will deploy a disaster assistance team to deliver “life-saving assistance,” Blinkin said.

Emphasizing the U.S. concern over the humanitarian crisis in the Tigray region, the U.S. ambassador to the United Nations, Linda Thomas-Greenfield, raised the issue in a series of bilateral meetings with U.N. Security Council members.

Alarm is growing over the fate of the Tigray region’s 6 million people as fighting is reportedly as fierce as ever between Ethiopian and allied forces and those supporting the now-fugitive Tigray leaders who once dominated Ethiopia’s government.

No one knows how many thousands of civilians have been killed since November when the conflict began. Humanitarian officials have warned that a growing number of people might be starving to death in Tigray.