GOMA, Democratic Republic of Congo — The United Nations knew Rwandan rebels were occupying villages in eastern Congo at the time the rebels raped nearly 200 women there, United Nations and aid officers said Wednesday, raising questions about why peacekeepers failed to move to protect villagers.

Between July 30 and Aug. 3, hundreds of soldiers from two rebel groups took over the villages, raping at least 179 women. Many of the attacks were gang rapes by two to six men. The humanitarian group that documented the rapes, International Medical Corps, said that it first notified the United Nations of the attacks on Aug. 6. The United Nations claims the group told it about the rapes on Aug. 12 for the first time. The U.N. made its first public comments on the rapes Sunday.

According to the officers, an e-mail alert from the United Nations Department of Safety and Security was sent to United Nations staff members on July 30, the day the rapes began. The message warned them to stay away from the area — part of Walikale, in the North Kivu Province of Congo — because it had been taken over by rebels.

“Everyone got that e-mail,” said an officer from a humanitarian organization in the area, who spoke on the condition of anonymity on strict instructions from the organization. “That rebel elements were active in those specific villages, and humanitarian workers should not go there.” The officer said that the alert did not mention rape.