KHARTOUM , Sudan ( CNN ) -- ( CNN ) -- Fighting resumed Tuesday in a disputed oil-rich town in Sudan , threatening to reignite a calamitous civil war which ended three years ago . Fresh fighting in Sudan over an oil-rich town has raised fears civil war could again erupt . Fresh fighting in Sudan over an oil-rich town has raised fears civil war could again erupt . UN Secretary General Ban Ki-moon deplored the fighting between the Sudanese military and troops with the Sudan People 's Liberation Army . The SPLA fought a rebellion against the government for more than 20 years until both sides signed a peace deal in 2005 . The deal 's Comprehensive Peace Agreement ended a north-south civil war that killed about 2 million people and displaced more than 4 million others . An impasse over the boundaries of the town of Abyei is a major reason the peace agreement has not been fully implemented . Fighting erupted in Abyei on May 13 . It resumed Tuesday despite a cease-fire and has `` resulted in the destruction '' of the town `` and the displacement of between 30,000 and 50,000 people , '' the secretary general said in a statement . Do n't Miss Sudanese opposition leader arrested Sudan cuts ties with Chad after attack Darfur rebels advance on Sudan capital , their leader says `` If the situation is not urgently addressed , the achievements thus far of the Comprehensive Peace Agreement could be placed at serious risk , '' he said . The civil war in Sudan , which started in 1983 , pitted a northern government dominated by Arab Muslims against black Christians and animists in southern Sudan . That conflict was not directly related to ongoing violence in the Darfur region of western Sudan . Human rights groups and United Nations say the Sudanese military armed and trained Arab militias in Darfur after a rebellion erupted in 2003 . They say the military and militias have engaged in widespread killing , rape and forced displacements in Darfur as they battle about rebels who have splintered into roughly a dozen groups . One of those groups staged a daring attack this month near the Sudanese capital , Khartoum . The government said it quashed the attack . Nearly 300,000 people have been killed and 2.5 million displaced in Darfur in the last five years , the UN says .
Fighting in disputed oil-rich Sudan town raises fears of return to civil war . Up to 50,000 people displaced by latest outbreak of fighting . Despite cease-fire agreement Abyei has been destroyed and deal is at risk .