The United Nations says it has confirmed government troops were responsible for raping dozens of women in the Democratic Republic of Congo last month.

U.N. spokesman Rupert Colville told reporters in Geneva Friday human rights investigators confirmed large-scale rape, pillaging and other crimes during a three-day rampage by troops in the country's South Kivu province.

He said the investigation confirmed at least 121 cases of rape in Nakiele on June 11, 12, and 13, and that investigators would be heading back to the area to get additional information and to try to identify the perpetrators.

Last week, the U.N.'s special representative on combating sexual violence blamed the attack on undisciplined Congolese security forces. At the time, Margot Wallstrom said more than 150 women had been raped.

The rapes were first reported by the medical aid group, Doctors Without Borders.

Some DRC officials and human rights groups have blamed the incident on a Congolese colonel, who led about 100 troops on a series of attacks in the area after deserting the army.

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.

In May, Congo asked the United Nations 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.