War crimes and crimes against humanity are still being committed in Ethiopia nearly a year after government and regional forces from Tigray agreed to end fighting, United Nations (UN) experts said in a report published on Monday.

Thousands died in the two-year conflict, which formally came to an end in November last year. Both sides accused each other of atrocities, including massacres, rape and arbitrary detentions, but each denied responsibility for systemic abuses.

"While the signing of the agreement may have mostly silenced the guns, it has not resolved the conflict in the north of the country, in particular in Tigray, nor has it brought about any comprehensive peace," Mohamed Chande Othman, chair of the International Commission of Human Rights Experts on Ethiopia, said in a statement accompanying the report.

"The situation in Ethiopia remains extremely grave," he added.

In its report, the Commission said human rights violations in Tigray were "grave and ongoing", and said there had been attacks by the Eritrean Defence Forces (EDF) against civilians.

Eritrea, which sent in troops to fight alongside the Ethiopian government forces during the conflict, has rejected accusations from residents and rights groups that its soldiers committed abuses in Tigray.

The Commission's report said violations "have been abetted or tolerated by the federal government, which has failed in its legal duty to protect its population from violations by a foreign army, or by Amhara militia present in the areas of Western and Southern Tigray."

The report said the Ethiopian National Defence Forces, Eritrean Defence Forces and allied regional special forces carried out a "widespread and systematic attack" against civilian populations.

"It finds that members of these forces committed the crimes against humanity of murder, torture, rape, acts of a sexual nature of comparable gravity, sexual slavery, enslavement imprisonment or other severe deprivation of liberty..." the report said.

Ethiopia's government and its armed forces have repeatedly denied that their soldiers committed widespread crimes on their own, or with Eritrean forces, and have promised to investigate complaints of individual abuses.

Authorities from the Ethiopian region of Amhara have also denied that their forces committed atrocities in neighbouring Tigray.