Conflict displaces 900,000 in Sudan border areas
United Nations urges Sudan government forces and rebels to let in badly needed aid
S.Sudan ratifies border deal with Sudan despite protest
Hundreds protest against demilitarisation of contested area
Darfur peace deal faces "huge challenges" - peacekeepers
Violence continues to plague Darfur despite deal between Sudan's govt and rebel group
Sudan army, rebels clash in oil border state
The fighting, which has been rumbling since June last year, has forced more than half a million people to flee