Sudan's army has withdrawn from the disputed region of Abyei bordering South Sudan, the United Nations confirmed on Wednesday, removing an obstacle to talks between the neighbours to end hostilities. But in a sign tensions were still running high, South Sudan accused its northern neighbour of keeping dozens of troops in the region dressed as police. Both sides have accused each other before of violating troop deployment agreements in Abyei. "The (U.N.) Secretary-General (Ban Ki-moon) welcomes the full withdrawal of the Sudan Armed Forces from the Abyei area...He calls on the Government of Sudan to withdraw all remaining armed police forces," an emailed U.N. statement said. South Sudan had already withdrawn its troops from Abyei, which has fertile grazing lands and extensive oil reserves - a major sticking point in negotiations after the split in July under a 2005 agreement that ended decades of civil war. -- SPA