Hundreds have died in ethnically motivated attacks by Sudan's paramilitary Rapid Support Forces (RSF) and allied militia in West Darfur, according to the UN's human rights chief.
"Such developments echo a horrific past that must not be repeated," said Volker Türk UN High Commissioner for Human Rights, marking "five months of futile suffering, death, loss and destruction."
Speaking at the UN Human Rights Council, Mr. Türk also warned of mounting civilian casualties, as 1500 have already lost their lives to what he called a pointless conflict.
The human rights chief highlighted the increase in indiscriminate attacks on civilians and civilian areas, including schools, homes and hospitals.
In past week alone more than 103 civilians have been killed during military operations by both parties in Khartoum and Omdurman, including many women and children.
Killed at home
"People are being killed inside their homes or when running to safety" said Radhouane Nouicer, the UN's human rights expert in Sudan.
Essential services have also been brought to a halt in areas affected by fighting and the paralysis of the economy has pushed millions to the brink of poverty.
Five months on, over five million have been uprooted from their homes and one million are seeking refuge in neighbouring countries.
"There is no reprieve in sight," said Mr. Türk.
Addressing the Geneva forum, Mr. Türk said he was "repulsed to hear of the ongoing epidemic of conflict-related sexual violence," as over 45 incidents with nearly 100 victims, including 19 children, were reported to the Office of the High Commissioner for Human Rights (OHCHR).
According to the data, the majority of perpetrators - around 78 per cent - have been men in RSF uniform or armed men affiliated with the RSF.
In response, UN Women called for every instance of sexual and gender based violence to be investigated, without any impunity.
OHCHR have also reported an increase in allegations from both sides of torture and killing of people outside combat.
Deploring the widespread cases of arbitrary detention, Mr. Türk said that "hundreds - and likely thousands - are being held incommunicado in appalling conditions."
Mr. Nouicer reported a "total disregard for international law and its principles" and cited violations to international law both by the Sudanese Armed Forces and the RSF.
Although promises have been made by both sides to investigate allegations, Mr. Türk said that "the silence has been deafening, with nobody held to account."
"It is time that the perpetrators of these gross violations are identified" and investigated, he insisted.
At present, access to areas affected by fighting are limited and humanitarian efforts are "callously blocked, denied-and directly attacked."
Since the start of fighting, the World Health Organization (WHO) has documented 56 attacks on healthcare facilities.
According to the UN, Sudan is now one of the most dangerous countries in the world for humanitarian workers, with 19 lives lost and several missing.
Many states, including Egypt - one of the largest hosts of Sudanese refugees - have repeatedly called for a ceasefire to allow aid to flow into the country.
Mr. Khalifa Ahmed, Prosecutor General of Sudan, responded to comments by calling on the international community to declare the militia a terrorist organisation, adding that Sudanese authorities were working to "put down the rebellion" and to ensure a ceasefire, humanitarian access and the return of those displaced.
Mr. Nouicer said that the world is "waiting for a revival of international diplomacy," adding that the conflict "would not end unless there is increased pressure from the international community."