An Afghan official says casualties are mounting in clashes between rival Taliban factions in the southeast of the country.

Gul Islam Sayal, the spokesman for the governor of Zabul province, said on Monday at least 47 fighters in all have been killed in three days of fighting. He says another 53 have been wounded and that at least 18 from a new, splinter Taliban group have been captured by the other side.

Several senior Taliban figures broke from the main insurgent group last week and elected Mullah Mohammad Rasool, formerly a Taliban governor, as "supreme leader."

Rasool's faction opposes Mullah Akhtar Mansoor, who assumed power after the announcement of the death of Taliban founder Mullah Mohammad Omar this summer. Mullah Omar is said to have been dead for two years.