It said those responsible should be prosecuted by the International Criminal Court (ICC) in The Hague.
Where genocide is found to have taken place, signatories to a UN convention are legally obliged to act to end it.
The report also said rebel forces in Sudan’s western region had committed serious human rights violations.
More than 70,000 people have been killed and two million more forced to flee their homes in Darfur since February 2003.
Khartoum denies arming the pro-Arab Janjaweed militias and blames Darfur’s rebel groups for starting the conflict.