A medical aid group says more than 100 women in the Democratic Republic of Congo were raped during a two-day attack in South Kivu province this month..

Doctors Without Borders says the rapes took place around the town of Fizi on June 10 through June 12.

A regional official with the group, Megan Hunter, said Thursday aid workers were cooperating with Congolese officials to get more information. She did not say who was responsible for the attacks.

Member of the provincial parliament Jean Marie Ngoma blamed the attacks on former rebels. He said 200 formers fighters with the Pareco rebel group had been integrated into the DRC army, but they recently deserted.

United Nations officials have previously called Congo “the rape capital of the world.” They say an atmosphere of impunity allows soldiers, rebel fighters, and civilians to rape women and children without fear of arrest.

Earlier this month, a top U.N. humanitarian official called on the international organization to “scale up” humanitarian aid.

Assistant Secretary-General for Humanitarian Affairs Catherine Bragg said some 600,000 Congolese have recently fled their homes due to attacks and insecurity.

Bragg said this new group of displaced people come largely from remote areas, where it is difficult for the U.N. and others to intervene.

Last month, the DRC asked the U.N. to withdraw its peacekeepers and allow the country to take over its own security, saying the country has made significant progress in reducing threats to the safety of citizens.

There are currently 20,000 U.N. peacekeepers in Congo.