Secretary of State Antony Blinken announced the State Department findings on the violence, which has included renewed attacks in Darfur two decades after a campaign there that was at the time branded by the United States as genocide.

Both the Sudanese army and the RSF "have unleashed horrific violence, death and destruction across Sudan," Blinken said in a statement.

"Civilians have borne the brunt of this needless conflict," he said.

The two sides "must stop this conflict now, comply with their obligations under international humanitarian and human rights law, and hold accountable those responsible for atrocities," Blinken said.

Brutal warfare including in the capital Khartoum erupted in April between the army, led by Sudan's de-facto leader Abdel Fattah al-Burhan, and the paramilitary RSF, commanded by Burhan's former deputy Mohamed Hamdan Daglo.

The violence came after the failure to integrate the RSF into the army, in line with a roadmap to civilian rule in a country that had been seeking to turn the page on decades of autocratic rule.

More than 10,000 people have been killed, according to a conservative estimate from the Armed Conflict Location and Event Data Project, a monitor, with the United Nations saying 6.3 million more have been forced to flee their homes.

Blinken said the RSF and allied militias "have terrorized women and girls through sexual violence, attacking them in their homes, kidnapping them from the streets, or targeting those trying to flee to safety across the border."

"In haunting echoes of the genocide that began almost 20 years ago in Darfur, we have seen an explosion of targeted violence against some of the same survivors' communities," Blinken said.

The United States and Saudi Arabia have led negotiations aimed at ending the fighting, with the State Department initially hesitant to take actions that could alienate one side and break down communication.

But the two sides made no tangible progress when they met again a little over a month ago in the Saudi port city of Jeddah.