Sudan's government and a collection of Darfur rebel groups have signed a cease-fire, opening the way for political negotiations ahead of a full peace agreement.

Gunmen killed five Rwandan soldiers in a series of attacks on the international peacekeeping force in Darfur, a spokesman for the mission said, marking a swift upsurge in violence in the western Sudanese region.

Obama Administration on Monday announced a new policy on Sudan, seeking a definitive end to conflict, gross "human rights abuses" and "genocide" in Darfur.

Two foreign aid workers seized at gunpoint more than three months ago in Sudan's Darfur region were released Saturday by their captors, a Sudanese government official said.

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.