A suicide bomb attack has killed at least nine people in north-western Pakistan, officials say. The blast went off at the entrance to an anti-Taliban commander's compound in Kurram, part of the tribal regions which border Afghanistan. The compound is used by a local militia and also contains residential units, reports the Reuters news agency. Pakistan's military has been carrying out operations against militant groups in the tribal regions for months. Three children were among the dead, tribal police officials told the Associated Press (AP). At least 15 people were injured. The compound belongs to a militant commander, Mullah Nabi, who split from the Pakistani Taliban. He has been involved in clashes in the past with other commanders loyal to the Taliban, says BBC Asia analyst Jill McGivering. The bomber tried to enter the guest quarters in Nabi's compound, tribal police official Amjad Khan told AP. When the bomber was challenged by guards outside, the explosives were detonated, he said. Mullah Nabi was unhurt, residents said. It is unclear who carried out the attack. Mullah Nabi used to belong to the Pakistani Taliban but broke away to form his own group. His main rival is another prominent commander, Mullah Toofan, a Taliban ally.