The clashes began on Thursday when gunmen attacked convoys of civilian vehicles, killing at least 40 people, mostly Shi'ite Muslims, triggering retaliatory attacks against Sunni residents, leading to intense battles between armed groups from both sides.

Government officials met with tribal leaders in northwestern Pakistan on Sunday to try to mediate a ceasefire between rival sectarian groups after days of clashes that have killed at least 68 people and injured dozens.

The clashes overnight between Sunni and Shiite tribes in Khyber Pakhtunkhwa Province came a day after gunmen ambushed a convoy of vehicles in the area.