The charges come a day after Sudan suspended the Islamist opposition.
Human Rights Watch in New York said in a statement, "The Sudanese military and government-backed militias are committing massive human rights violations daily in the western region of Darfur" against the African population.
Georgette Gagnon, deputy director for the Africa division of Human Rights Watch, said, "The government's campaign of terror has already forcibly displaced 1 million innocent civilians, and the numbers are increasing by the day."
The report was issued a day after the government suspended the main opposition Popular National Congress, alleging it was planning a coup. The PNC's Islamist leader Hasan al-Turabi was arrested Wednesday on suspicion of seeking to topple the regime.
A former leader of Lt. Gen. Umar Hassan Ahmad al-Bashir's regime, Turabi was freed in October 2003 after spending nearly three years under house arrest.