Four United Nations workers, who've been detained by pro-government militia in southern Sudan since their plane was seized a week ago, have been freed.

A UN spokesperson said they were exhausted but well.

Three of them -- an American working for the United Nations Children's Fund, UNICEF, and two Kenyan pilots, were flown to a UN base at Lokichokio in northern Kenya.

The seizure of the UN team had led to a suspension of aid to the region, Fanjak in Upper Nile state.

From the newsroom of the BBC World Service