Her office had received reports that more than 100 protesters were killed and many more injured during an assault by security forces on a peaceful sit-in outside the defense ministry on June 3, she said, Reuters reported.
Sudan's uprising "has been met with a brutal crackdown by the security forces this month," Bachelet said in a speech opening a three-week session of the UN Human Rights Council in Geneva.
Sudan's ruling military council said on Sunday that Ethiopia and the African Union needed to unify their efforts to mediate between the council and an opposition coalition on the structure of the country's transitional government.
The generals and the opposition have been wrangling for weeks over what form Sudan's transitional government should take after the military deposed long-time president Omar al-Bashir on April 11.