The national flag carrier confirmed in a statement that Flight PK-661 had lost contact with air traffic controllers Wednesday afternoon.
Laiq Shah, a senior police official in Khyber-Pakhtunkhwa province told Reuters by telephone that the plane had crashed in that region, near the town of Havelian.
He said rescue personnel were en route to the scene.
Initial reports said there were 37 passengers on the plane, however reports from Geo News and Dawn News channels both reported 47 people were on board the missing aircraft.
Geo News, citing civil aviation sourecs, said the plane lost contact with civil aviation authority at around 4.30pm (11.30 GMT).