At least 542 civilians have been confirmed killed in Sudan's North Darfur region in the past three weeks, the United Nations said, warning the actual death toll was likely "much higher".
"The horror unfolding in Sudan knows no bounds," UN rights chief Volker Turk said in a statement on Thursday, referring to the country's ongoing civil war.
Darfur in particular has become a key battleground in the war that erupted on April 15, 2023 between the regular army, led by Abdel Fattah al Burhan, and the Rapid Support Forces (RSF), headed by his former deputy Mohamed Hamdan Dagalo.
The war has left tens of thousands dead and triggered what aid agencies describe as the world's largest displacement and hunger crises.
The battle for El-Fasher, the last major city in Darfur to elude RSF control, has intensified in recent weeks as the paramilitaries have sought to compensate for their loss of the capital Khartoum last month.
Turk pointed to an attack three days ago by the RSF on El-Fasher and the Abu Shouk camp that killed at least 40 civilians.
"This brings the confirmed number of civilians killed in North Darfur to at least 542 in just the last three weeks," he said.
"The actual death toll is likely much higher."
Alarming reports of executions
Turk cited "the ominous warning by the RSF of 'bloodshed' ahead of imminent battles with the Sudanese Armed Forces (SAF) and their associated armed movements."
"Everything must be done to protect civilians trapped amid dire conditions in and around El-Fasher."
He also highlighted "reports of extrajudicial executions in Khartoum state", which he described as "extremely disturbing".
"Horrific videos circulating on social media show at least 30 men in civilian clothing being rounded up and executed by armed men in RSF uniforms in Al-Salha in southern Omdurman," he said, adding that in a subsequent video, "an RSF field commander acknowledged the killings."
Those videos came after "shocking reports in recent weeks of the extrajudicial execution of dozens of people accused of collaborating with the RSF in southern Khartoum, allegedly committed by the Al-Baraa Brigade", a pro-SAF militia, Turk said.
"Deliberately taking the life of a civilian or anyone no longer directly taking part in hostilities is a war crime," he insisted.
The UN rights chief said he had "personally alerted both leaders of the RSF and SAF to the catastrophic human rights consequences of this war".
"These harrowing consequences are a daily, lived reality for millions of Sudanese. It is well past time for this conflict to stop."

The war in Sudan is far more than a simple battle between two armed factions. It is a complex and multifaceted struggle, deeply entrenched in internal rivalries and exacerbated by external interference.