Both players were among seven cricketers dropped and sent home after Pakistan’s 194-run defeat to England at Lord’s.
They were summoned by the NCCIA, with at least one player reportedly questioned for several hours. One of them has also been given a questionnaire to complete and return next week.
It remains unclear what prompted the questioning or whether it is linked to the Pakistan Cricket Board’s separate internal disciplinary inquiry into players’ conduct during the England tour.
Rizwan struggled with the bat, scoring 12, 41, 7 and 1 across the two Tests, while Imam was ruled out at Lord’s with a calf injury.
PCB chief selector Aaqib Javed had publicly questioned Imam’s injury and indicated that an inquiry could follow.
The PCB has also sought explanations from selectors over the inclusion of both players in the West Indies and England squads.
Former captain Misbah-ul-Haq resigned from the selection panel following the sweeping changes.