Several hundred people demonstrated in Lahore and hundreds also demonstrated in Pakistan's commercial hub Karachi

Clashes have erupted over several months between Sunni and Shiite Muslim tribes in the area, which was formerly semi-autonomous

Tribal and family feuds are common in Sunni-majority Pakistan, where the Shiite community has long suffered discrimination and violence

Thursday's attacks also left 16 people wounded, 11 of whom were in critical condition, senior administrator Javed Ullah Mehsud told AFP

"A curfew has been imposed on the main road connecting Upper and Lower Kurram, and the bazaar remained completely closed, with all traffic suspended," an official said

The latest violence drew condemnation from officials and human rights groups. "The frequency of such incidents confirms the failure of the federal and provincial governments to protect the security of ordinary citizens," the independent Human Rights Commission of Pakistan (HRCP) said