On Monday the Islamic state group claimed responsibility.
“A suicide attacker from Islamic State … detonated his explosive jacket in the middle of a crowd” in Khar, the jihadist group’s news arm Amaq said in a statement on Monday.
The attack occurred in the town of Khar in the northwestern Bajaur district, just 45km from the Afghan border, in an area where militancy has been rising since the Taliban took control of Kabul in 2021.
Parliament is likely to be dissolved after it completes its term in the next two weeks, with national elections to be held by mid-November or earlier.
The local chapter of the jihadist Islamic State group has in the past targeted JUI-F rallies and leaders.
On Monday, blood-stained shoes and prayer caps littered the site, along with ball bearings and steel bolts from the suicide vest.
Pieces of human flesh could still be seen, blasted 30m from the stage where the bomber detonated his device.
Thousands of mourners attended the first funeral ceremonies, including for two young cousins aged 16 and 17.
“It was not easy for us to lift two coffins. This tragedy has shattered our family,” said Najib Ullah, the brother of one of the boys.
“Our women are profoundly shocked and devastated. When I see the mothers of the victims, I find myself losing my own courage.”