The Southern Sudanese rebel leader George Athor has been killed, according to a report Tuesday.

The Sudan Tribune website on Tuesday quoted South Sudan's Vice President Riek Machar Teny as saying that Athor was killed on Monday in Morobo near South Sudan's capital Juba.

Earlier Tuesday, Athor was reported to be under siege by South Sudan's army, Sudan People's Liberation Army (SPLA), in Morobo in Central Equatoria state.

The circumstances of his alleged death are unclear at the moment, but Athor's rebel group on Sunday claimed it had thwarted an attempt to kill him.

One of Athor's wives told the Sudan Tribune earlier that she suspected her husband had already been killed, as she had lost contact with him since Monday.

The rebel leader recently threatened to wage more attacks in South Sudan, including his forces' intention to capture Bor, capital of the Jonglei state. The move came after the failure of secret talks with Juba authorities held in Kenya's capital Nairobi last November.