Pakistani officials say Sunni and Shi'ite militants are battling each other for a third day in the country's North-West Frontier Province.
A Pakistani administrator in the tribal region, Sahibzada Mohammed Anis, says the confirmed death toll from the fighting is 15, with scores of people wounded. On Saturday, another official said 40 people had been killed.
The administrator says tribal elders are trying to negotiate an end to the violence.
Heavy fighting between majority Sunnis and minority Shi'ites erupted Friday in and around the town of Parachinar in the semi-autonomous Kurram region.
Pakistani officials say the fighting in Parachinar subsided Saturday after the military imposed a curfew and government helicopters patrolled the area. But, they say battles continued Sunday in nearby villages.
The cause of the sectarian violence has not been independently confirmed, but residents say it began after one group held a demonstration denouncing the other sect.
Some information for this report was provided by AP and Reuters.