By Amber Henshaw
BBC News, Khartoum
Sudan must overhaul its legal system to stop mass rape from being committed in the war-torn region of Darfur, an aid agency says in a report.
More than 2m people have fled their homes in Darfur
Rape victims have almost no access to justice and even risk being prosecuted for having had sex outside marriage.
Refugees International said government soldiers and affiliated militias were often responsible for the rapes.
Khartoum denies that rape has been used as a weapon of war in Darfur and says Sudan already punishes rape harshly.
More than 2m people have been displaced from their homes since the conflict began four years ago - and it is thought that at least 200,000 people have died.
Refugees International said the government was more likely to take action against those who reported and documented rape than those who committed it.
Its report said the Sudanese rape laws needed to be completely revised to protect women and girls from systemised sexual attacks.
The report said the high incidence of sexual violence in Darfur had been well documented in the past, but existing regulations made it "all but impossible" to prosecute rapists.
African peacekeepers struggle to protect vulnerable civilians
It added that women who admitted being raped also risked being prosecuted themselves for having sex outside marriage - an offence punishable by 100 lashes or death by stoning.
The report made 24 recommendations for change, including the need for more judges to be trained and more female police officers to be recruited.
The report also urged Sudan to expand its definition of rape to include sexual assault with objects, including rifle barrels.
It said courts should also give equal weight to the evidence of both men and women.
Researchers said the report was based on interviews with lawyers and aid workers in the capital, Khartoum.
The Refugees International team said it was refused permission to visit Darfur and told to stop working by Sudanese authorities eight days into their mission.