South Sudan's armed opposition has released a civil society activist whom they had detained for a week.

SPSA-In Opposition forces loyal to Riek Machar arrested Dombek Aniel, the executive director of Abyei Community Action for Development, earlier this week in Leer, Unity State, reported local radio in Abyei.

It is not clear why Aniel was arrested by the SPLA-IO.

ACAD's field coordinator Lual Kuol Lual said his boss is now in Juba.