Sudan accused neighbouring Chad of supporting Darfur-based rebels who launched an attack near the capital Khartoum in May that was the closet they had ever come to hitting the seat of Sudan's government.

Sudan cut diplomatic ties with Chad immediately afterwards and Chad in turn closed its border with Sudan and halted bilateral trade.

Wade had brokered a peace agreement in Dakar in March that was signed by the presidents of Sudan and Chad.

The deal was meant to suppress attacks by armed groups operating along their shared border, but it has failed to ease instability in the region.