Sudan's army denies aircraft downed in S. Kordofan
Northern and southern presidents due to meet in Ethiopia
Violence roils Sudan oil state, leaders to hold talks
Residents fleeing Southern Kordofan capital Kadugli - U.N.
North, south Sudan leaders to hold Abyei talks
Tensions high since Khartoum seized the disputed region of Abyei on May 21
S.Sudan accuses north of air attack, clashes flare
Up to 40,000 people may have fled clashes in the volatile Southern Kordofan state