Amnesty International has called on the opposing sides in Sudan’s conflict to stop committing war crimes.
It says civilians are dying in large numbers as a result of deliberate and indiscriminate attacks.
The rights group interviewed dozens of people, most of whom had fled from the Darfur region to camps in Chad.
It says scores of women and girls, some as young as 12, have been subjected to sexual violence, including rape.
Amnesty found that the perpetrators in most cases were fighters from the Rapid Support Forces and allied Arab militias.
UN agencies and NGOs are warning that the number of people in Sudan facing an acute shortage of food is expected to reach more than 20 million, which is over 40% of the population.