Manan Niazi said today that Mullah Mansoor Dadullah is "seriously wounded" but gave no further details.
Officials in Zabul province, where rival Taliban groups have been fighting for a week, said Dadullah was killed in an ambush Wednesday.
Dadullah is deputy leader of a dissident Taliban faction set up on November 1 with the election of Mullah Mohammad Rasool as leader. It's unclear how much support it has.
The breakaway faction opposes Mullah Akhtar Mansoor, who took over in August after the death of founder Mullah Mohammad Omar was announced. Niazi says Dadullah helped broker an alliance between their faction and Islamic State militants, who have a growing presence in Afghanistan.