A leaked African Union report calls for South Sudan's president and his main rival to be barred from a transitional government and for the war-torn country to be placed under AU control.
Reuters news agency published an account of the report Friday as another round of talks to end South Sudan's 15-month conflict ended in Addis Ababa without a peace deal.
U.S. State Department spokeswoman Marie Harf said the leaders of South Sudan have "again failed" its people.
Harf said the the conflict in South Sudan has resulted in a "tragedy for its people" and "a humanitarian catastrophe." She said the U.S. "strongly" condemns "the lack of political leadership to resolve this man-made conflict" and is looking forward to the U.N. Security Council's planned review of the situation.
According to Reuters, the AU report says President Salva Kiir and former vice president-turned-rebel leader Riek Machar should be barred from roles in a "transitional executive" body, along with all the ministers in power before the Cabinet was dissolved and Machar was dismissed from office in July 2013.
The report recommends creation of an AU-appointed and U.N.-backed panel to oversee a five-year transition for South Sudan. Oil revenue would go into an escrow account overseen by the African Development Bank.
Reuters says the AU report also calls for creation of an African peacekeeping force made up of troops "without prior involvement or direct interest in South Sudan."
There was no immediate response from the South Sudanese government. A rebel spokesman in Addis Ababa, Puot Kang Chol, called for the full report to be released.
"We have seen that and we have been demanding the publishing of that report," he said. "And we continue to demand the same - we want that report published so that we see it in full. We have not seen it in full, we have seen only part of it and we are not worried about the report. But we want to see it, we want it published officially."
The spokesman also said that if Machar is to be excluded from the transitional government, "there must be a legal basis for that."
Fighting erupted in South Sudan in December 2013, six months after President Kiir fired Machar as vice president. The fighting exposed ethnic divisions in the country with the Dinka tribe supporting Mr. Kiir and the Nuer tribe backing Machar.
Repeated cease-fires have failed to take hold. The fighting has killed tens of thousands of people and displaced nearly two million.