The United States presented the warring Sudanese army and paramilitary Rapid Support Forces (RSF) with a strong text for a peace plan but neither side has accepted it, senior US envoy Massad Boulos said on Tuesday.

Trump said last week he would intervene to stop the devastating conflict, which broke out in April 2023 and has spread famine and ethnic killings across the country and threatened a split, the second in its history.

Previous efforts led by the United States, Saudi Arabia, Egypt, and the United Arab Emirates have failed to bear fruit. The group submitted a proposal to the two forces in early November.

Boulos, US President Donald Trump's advisor for African and Arab affairs, said both Sudan's warring factions had welcomed the US plan but neither had formally accepted the text.

On Sunday however, army chief Abdel Fattah al-Burhan described the US's latest proposal as the worst he'd seen, saying it sidelined the army and granted the RSF legitimacy.

Boulos, speaking at a press conference in Abu Dhabi, said the army had come back with "preconditions" but the US wanted the plan accepted in its original form.

Meanwhile, on Monday, RSF chief Mohamed Hamdan Dagalo said his forces would enter into a unilateral ceasefire immediately. It was unclear on Tuesday whether that ceasefire held. 

Boulos said he welcomed the RSF's declaration and hoped it would be upheld, and said Burhan's criticisms were based on the wrong facts.