United Nations: Rape is being used as a weapon of war in Sudan's war-torn Darfur region
It details numerous cases of rape by government soldiers, including one in which girls as young as 13 and pregnant women were sexually assaulted.
The UN's human rights chief called on Sudan's government to investigate and prosecute those responsible.
A second UN report details the seizure and disappearance of men in Darfur suspected to be rebel supporters.
At least 200,000 people have been killed and 2m displaced during the four year conflict between rebel groups and government-backed militia.
The BBC's Imogen Foulkes in Geneva says the new reports released by UN Human Rights Commissioner Louise Arbour make grim reading.
The UN office has a team of human rights monitors in Darfur who report regularly on the situation there.
At least 15 women in and around the village of Deribat report being raped by soldiers during an attack last December.
In their report the human rights monitors conclude that rape was used as a weapon of war, a clear violation of the Geneva Conventions.
Ms Arbour called on Sudan's government to conduct an independent investigation into the attacks and to ensure that those responsible are prosecuted.
The second report details the enforced disappearance of at least 19 men in south Darfur.
The UN monitors say they were taken from their homes late last September by government forces who claimed the men were rebels. Since then only three have returned.
At least eight were identified among a group of corpses exhumed earlier this year.
Ms Arbour says no circumstances justify enforced disappearance and summary execution and has called for detailed explanations from the authorities in Darfur.
Our correspondent says the new reports will add to the pressure on Sudan to address the violence in Darfur.
Last week the UN Human Rights Council ordered an investigation into Sudan's compliance with international conventions against torture, summary execution and violence against women.
UN rights chief demands probe in Darfur rape cases