The US envoy to Sudan on Monday said there had been a marked improvement of aid deliveries into the war-torn African country suffering a devastating humanitarian crisis.
Fighting erupted in April 2023 between the regular army and the paramilitary Rapid Support Forces (RSF) after a plan to integrate them into the military failed.
Both sides have been accused of war crimes, including deliberately targeting civilians and blocking humanitarian aid.
"We are pleased by the significant but incremental improvements on humanitarian access," US envoy on Sudan, Tom Perriello, told reporters in Nairobi.
"We have had a couple (of) hundred trucks get through areas that were previously blocked."
More than 25 million people -- more than half of Sudan's population -- face acute hunger, according to UN agencies, with famine declared in a displacement camp in the western Darfur region, which borders Chad.
The war has already killed tens of thousands of people, with the World Health Organization declaring a toll of at least 20,000 people dead, but some estimates are up to 150,000.
"The situation is extremely dire and those who are in the best position to stop it seem eager instead to accelerate" it, Perriello said.
Several rounds of peace negotiations have failed to end the fighting.
Multiple truces brokered by the United States and Saudi Arabia in the early stages of the war were systematically violated and the process faltered.
"One track of these efforts overall is a sense of trying to restore the basic norm that even if the war continues, certain issues of humanitarian access and civilian protection should be respected," Perriello said, blaming "a lack of sufficient will" from the warring sides.
The latest round of US-brokered talks opened in Switzerland last month.
While an RSF delegation showed up, the Sudanese armed forces were unhappy with the format and did not attend, though they were in telephone contact with the mediators.
The talks were co-hosted by Saudi Arabia and Switzerland, with the African Union, Egypt, the United Arab Emirates (UAE) and the United Nations completing the so-called Aligned for Advancing Lifesaving and Peace in Sudan Group (ALPS).
The army objected to the UAE's involvement in the talks, accusing the oil-rich Gulf state of arming the RSF. The UAE has repeatedly denied the allegations.
The Sudanese army on Monday rejected an accusation by the UAE that it had attacked the home of its ambassador in Khartoum.