GENEVA (AP) — The head of a U.N.-backed fact-finding team looking into human rights violations and abuses in Sudan said Friday it found the paramilitary Rapid Support Forces responsible for large-scale sexual violence in areas that it controls.

Mohamed Chande Othman has denounced “staggering violence” in Sudan since war broke out more than 18 months ago between the Sudanese military and the RSF, starting with open fighting in the capital, Khartoum, that later spread across the country.

“We said in our report that we attribute sexual gender-based violence to RSF in West Darfur, in Darfur, in greater Khartoum, and in al-Gezira (state),” the Tanzanian lawyer said Friday by phone from Zimbabwe, where he was attending a conference.

However, Othman said a renewed mandate from the U.N. Human Rights Council would allow his team of independent experts to investigate “credible” allegations of sexual exploitation by the Sudanese armed forces as well.

The fact-finding mission on Tuesday released a more comprehensive version of its report presented in September to the rights council, which has 47 member countries. The broader report cited gang rapes, sexual slavery and the abduction of victims in areas the RSF controls.

“It’s important to highlight the horrendous nature and the widespread nature - the patterns of violence - that were committed,” Othman said.

His team found the sexual violence and allegations of enforced marriages and human trafficking across borders for sexual purposes took place mostly during invasions of towns and cities.

“Victims and witnesses consistently reported that perpetrators threatened them with weapons, including firearms, knives and whips to intimidate and coerce them,” the latest report said, citing violence like punching, beatings with sticks, and lashing before and during rape.

“Men and boys were also reportedly targeted while in detention with sexual violence, including rape, threats of rape, forced nudity and beating on the genitals, requiring further investigation,” it added.

The violence in Sudan has been unrelenting. On Sunday, a doctors group and the United Nations reported that RSF fighters riot in east central Sudan carried out? took part in? a multi-day attack that killed more than 120 people in one town.

On Tuesday, the U.N. migration agency said 14 million people - or over 30% of the country’s population - have been displaced either within Sudan or abroad because of the conflict, making it the world’s largest displacement crisis.