The blast occurred in a coal mine in Doli area of Lower Orakzai Agency. At least five labourers were killed and six others injured in the explosion.
The injured and bodies were being shifted to nearby hospital.
The official said the political administration had closed the mines after March 20 incident and the owner restarted mining without formal permission.
The official confirmed that the rescue workers had pulled out six injured miners and besides five bodies.
Ambulances have been dispatched to the area to shift the injured and bodies to hospital.
The labourers hailed from Shangla district, Khyber Pakhtunkhwa.