The United Nations human rights chief on Friday said another human rights catastrophe was unfolding in Sudan, in the city of El-Obeid in North Kordofan, and urged the world to act.

"The signs from El-Obeid are clear and unmistakable: Another human rights catastrophe is unfolding in Sudan, this time in the capital of the strategic state of North Kordofan," the U.N. high commissioner for human rights Volker Turk told delegates in Geneva during an urgent debate at the U.N. human rights council on the situation in the region.

The urgent debate was called by Britain, whose envoy previously warned of the risk of large-scale atrocities following reports that Sudan's paramilitary Rapid Support Forces and ​allies are massing forces around the city of El-Obeid, which could result in an escalation of the conflict.

The UN, on Monday, warned that El-Obeid could soon come under siege as the Rapid Support Forces (RSF) mass troops around the city ahead of what aid officials fear could be a major ground assault.

Siege-like conditions

Turk told delegates that civilians have been subjected to siege-like conditions for 18 months, with shortages of clean water reaching a critical point in al-Obeid amid relentless drone strikes as the Sudanese Armed Forces and the RSF battle for control over areas surrounding the city.

The warning raised concerns that El-Obeid could suffer the same fate as Al Fasher in Darfur, where the RSF captured the city after a prolonged siege. The UN has said the October assault on Al Fasher bore "the hallmarks of genocide."

At least 45 civilians were killed and 41 injured in 15 drone strikes in al-Obeid and surrounding areas between June 6-28 recorded by the UN human rights office.