Africa's latest effort to resolve an 18-month-old conflict in Sudan's western Darfur region hit an immediate bump on Monday when the Sudanese government rejected a proposal for African Union (AU) troops to disarm rebel groups while Khartoum dealt with the pro-government Janjawid militia. Nigerian President and current chairman of the African Union, Olusegun Obasanjo, had floated the idea ahead of the latest round of AU-sponsored peace talks which opened in the Nigerian capital Abuja on Monday.