Some 5,000 people have sought refuge in Gereida town over the past week, following violent clashes in the conflict-torn western Sudanese state of South Darfur that had already displaced 15,000, the international NGO Oxfam reported. "We are now estimating that between 18,000 and 20,000 IDPs [internally displaced persons] have newly arrived in Gereida, although the number hasn't been officially confirmed yet," Nicki Bennett, spokeswoman for Oxfam in Sudan, said on Wednesday.