South Sudan has called on the U.N. Security Council to set a deadline for Sudan to withdraw its troops from the disputed region of Abyei or be held \"accountable.\" Amid rising fears of border clashes between the two states, which split this year, the United Nations asked for more helicopters and aircraft to monitor the frontiers around the resource rich territory. Sudan took control of the frontier region in May, forcing 110,000 residents to flee to South Sudan. \"The Sudan Armed Forces must now withdraw immediately and unconditionally from Abyei area,\" South Sudan’s U.N. envoy, David Buom Choat, told a council meeting on the disputed territory. \"We respectfully request the council to set a deadline for this withdrawal, and to hold whoever violates the deadline accountable,\" he added. Sudan has missed one accord to pull out of Abyei by Sept. 30. Sudan’s U.N. ambassador, Daffa-Alla Elhag Ali Osman, told the council the forces would only leave when a deployment of U.N. peacekeepers to the territory has been completed. About 1,780 Ethiopian troops out of a full force of 4,200 are already in Abyei where there have been several clashes this year. The Khartoum envoy said the withdrawal could also be held up by the rainy season. The U.N. has insisted the troop withdrawal accord between the north and south, made on Sept. 11, does not state that all peacekeepers had to be present before a withdrawal. Choat said South Sudan’s army had withdrawn from Abyei, but the new head of U.N. peacekeeping Herve Ladsous, making his first appearance at the council, said South Sudanese forces were still in the territory. Ladsous called on the council to press both sides to withdraw their troops. South Sudan declared itself independent from Sudan in July following a referendum earlier this year. The two fought a two decade civil war up to 2005 in which two million people were killed. The U.N. Security Council set up the U.N. mission in Abyei, UNISFA, after Sudan moved troops in. U.N. Secretary General Ban Ki-moon has proposed changing the UNISFA mandate so that it can take up a stronger border observer missions. Ladsous said the force would also require four extra helicopters and two planes to carry out the work.