CNN reported Saleem Murrawat, the police chief of the Lower Dir district of Khyber Pakhtunkhwa province, said the funeral was for a member of a pro-government, anti-Taliban militia in the Jandol area near the border with Afghanistan.
Murrawat said the suicide bomber, about 18 years old, was standing among mourners at the funeral procession when the attack occurred.
CNN reported a spokesman for Tehreek-i-Taliban Pakistan said the group claimed responsibility for the attack. The spokesman, Mohammad Talha, said the attack was in response to growing support for local resistance groups against the Taliban in the region.
Northwest Pakistan and its capital, Peshawar, have been the scene of increased militant violence in recent years, resulting in the deaths of hundreds of people.