"It [the lack of respect for ceasefire] is also because both parties still think that they can win that war ... The both sides have realized that even if they win, it will not be a quick war, and a dragged out long war could damage the entire country," Perthes told a briefing.
The two sides, the Sudanese regular armed forces and the Rapid Support Forces (RSF) paramilitary group, vowed to continue talks on a ceasefire with the mediation of Saudi Arabia and the United States, the UN official added.
"They told me that they intend to stay and continue discussion on real ceasefire ... A real ceasefire would have to go along with a monitoring verification mechanism," Perthes stated.
On April 15, violent clashes broke out between the armed forces and the RSF, with the epicenter located in Khartoum. The government forces accused the RSF of mutiny and launched airstrikes against their bases. Abdel Fattah Burhan, the head of the Sudanese military, issued a decree disbanding the RSF.
The parties have since introduced a number of temporary nationwide ceasefires, but the conflict has not been settled yet.
On Thursday, the Al Arabiya broadcaster reported that the Sudanese military and the rebel RSF had signed an agreement in which they had committed to doing everything possible to avoid injuring civilians. The deal followed six-day negotiations in the Saudi Arabian city of Jeddah.
So far, around 604 people have died and over 5,000 others have been injured in the clashes in Sudan, the World Health Organization said on Tuesday.