UNICEF estimates rebels of the Lord's Resistance Army have abducted between 6,000 and 8,000 children over the last 4 years. About 1/2 have returned home, 1/4 remain in captivity and the rest are "almost certainly dead," UNICEF executive director Stephen Lewis said from his headquarters in Geneva.

The Lord's Resistance Army has been fighting for nearly a decade to overthrow the government of Uganda. Uganda accuses neighboring Sudan of giving arms, money and training to the rebels who launch cross-border raids from southern Sudan.

Lewis praised Sudan on Friday for helping to fly back to Uganda 17 people -- mostly children -- who escaped from the rebels.

"It is our profound hope that this experience will be repeated, and that we can now begin to work with the government of Sudan to locate all of the other children who are still held in captivity and to arrange for their return to northern Uganda," Lewis said.

In Kampala, military spokesman Lt. Shaban Bantariza said the army had rescued 500 children since January. Most of the children were collected after crossing the Sudanese border, he said.