Ethiopia's Gondar University has denied reports that some of its experts helped Amhara militia destroy evidence of mass graves containing bodies of Tigrayans.
Witnesses told the BBC that they had seen the experts advise militia members.
In a letter to the BBC, the university described this as an "unsubstantiated accusation".
It also denied that there was any evidence that the bodies of Tigrayans had been found in mass graves.
If anything like that had been discovered then the "research team... would have been the first to acknowledge and provide the evidence", the university said.
"The university is one of the most respected research-based educational institutions in Ethiopia which is devoted to solving some of society's most pressing issues," it added.
As part of its research, Gondar University's experts have found mass grave sites in the area, but it has discovered that these were the result of the killing of thousands of ethnic Amharas carried out by the Tigray People's Liberation Front (TPLF) since the mid-1990s.
The TPLF was once the dominant political party in Ethiopia, but that changed when Abiy Ahmed became prime minister in 2018.
In November 2020, the political tension between the federal government and the TPLF, which controls most of the northern Tigray region, led to the outbreak of civil war.
All sides in the on-going conflict have been accused of carrying out mass killings.
Witnesses had described to the BBC how, in western Tigray, an area under the control of forces from the neighbouring Amhara region, the bodies of ethnic Tigrayans in freshly dug mass graves had been exhumed and destroyed. This came ahead of a possible visit by UN investigators looking into war crimes.