A dozen top United Nations officials on Monday called for a stop to indiscriminate and targeted attacks against civilians in Ethiopia's northern Tigray region, particularly calling out reports of rape and "other horrific forms of sexual violence."

In a joint statement the officials, including UN aid chief Mark Lowcock, rights chief Michelle Bachelet and refugee chief Filippo Grandi, called on the warring parties to protect civilians from human rights abuse, condemn sexual violence and hold perpetrators accountable.

"It is essential that an independent investigation into conflict-related sexual violence in Tigray be initiated, with the involvement of the UN Office of the High Commissioner for Human Rights," the statement said.

Fighting between government troops and the region's former ruling party, the Tigray People's Liberation Front (TPLF), has killed thousands of people and forced hundreds of thousands from their homes in the mountainous region of about 5 million.

The United Nations has raised concerns about atrocities being committed in Tigray, while US Secretary of State Antony Blinken has described acts carried out in the region as ethnic cleansing. Ethiopia has rejected Blinken's allegation.

The UN officials said initial assessments of 106 health facilities in Tigray between December 2020 and March 2021 showed that nearly 70% had been looted, 30% were damaged, and only 13% in Tigray were functional.

"Preventing and responding to the grave human suffering resulting from this conflict will require a concerted effort at all levels," they said. "When it comes to getting aid staff and supplies into Tigray ... much more remains to be done."