A United Nations human rights mission on Monday accused the government of Sudan of orchestrating and taking part in international crimes in Darfur.
The mission, led by Nobel peace prize laureate Jody Williams, was sent by the UN Human Rights Council to investigate allegations of widespread abuse in the vast western region of the country.
"The mission further concludes that the government of Sudan has manifestly failed to protect the population of Darfur from large-scale international crimes and has itself orchestrated and participated in these crimes," the mission said.
The Darfur violence, described as genocide by Washington in a term Khartoum rejects, has driven 2.5 million people from their homes and killed an estimated 200,000 since rebels took up arms in 2003.
Khartoum says those numbers are exaggerated and accuses the Western media of blowing the conflict out of proportion.
The decision to send the six-strong mission was taken by the UN's human rights watchdog following a bitter debate last December. But after first agreeing to cooperate, the Sudanese government refused entry visas for the team.
The mission traveled instead to the Chadian border with the western Sudan region and to Addis Ababa, headquarters of the African Union which has been trying unsuccessfully to contain the violence in Darfur with a few thousand peace monitors.
"The situation is characterized by gross and systematic violations of human rights and grave breaches of international humanitarian law," the mission said.