Over 80 people were killed and scores more injured in recent sectarian clashes in northwestern Pakistan. Experts say historic rivalries, extremist Islamist groups, and political marginalization are to blame.

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.

More than 80 people have been killed in renewed sectarian violence in north-west Pakistan, officials say. Another156 are said to have been wounded in three days of fighting in the tribal district of Kurram,