UN secretary general Ban Ki-Moon is alarmed about reports of a military build up appearing in the disputed border region of Abyei.

He described the situation as violating the agreement reached in June when both Kharttoum and Juba said they would withdraw their troops from the region.

A UN spokesman said the secretary general was 'alarmed at reports' he had received earlier this week about armed militias being mobilised in Abyei.

He said Ki-Moon calls on the Sudanese government to ensure full and immediate withdrawl of these armed groups from the region.