JUBA - Several soldiers were killed in clashes between south Sudan's army and rebel militia in oil-producing Unity State, the army said on Friday. Ahead of independence in July, analysts have warned south Sudan must maintain security to avoid becoming a failed state and destabilizing much of the region. At least seven rebel militia are fighting the southern army (SPLA) across Sudan's south, where more than 800 people have been killed this year from the clashes and traditional tribal conflicts, the United Nations has said.