New York - A survey of dozens of women who fled violence in Darfur found that a third of them reported or showed signs of rape, and revealed a widespread fear of sexual violence in their refugee camp in Chad, a human rights group reported on Sunday.

About half the rapes were carried out in Darfur by janjaweed militiamen allied to the Arab-dominated government in Khartoum, and half were assaults by Chadian villagers near the UN refugee camp, usually when the women left to search for firewood or herd livestock, according to the report by the Unites states based group Physicians for Human Rights.

The group reached the 88 women included in the survey through camp leaders and by word-of-mouth, a sampling method the report said hinders drawing general conclusions about the prevalence of rape in Darfur or in the Farchana refugee camp in Chad.

Recording rape or interviewing victims of sexual violence is problematic in Darfur's Muslim culture, where women fear social stigma or further trauma and sometimes recant their allegations out of shame. Further complicating the effort, women displaced inside Darfur live mostly in government-controlled areas and fear reprisal.

The issue is highly contentious for the Sudanese government, which denies any systematic rape or violence against women.