According to law, ECC is expected to complete adjudication of complaints within 15 days which will end on coming Thursday.
ECC chairwoman Zuhra Bayan Shinwari told a press conference that the process would possibly miss deadline, citing high number of complaints.
More than 16,500 complaints were lodged following the announcement of long-delayed preliminary results on December 22.
The complaints have been placed in 16 different categories, most of which (6,881) are about difference between biometrically verified votes and results sheets.
Moreover, 3,727 complaints suggest electoral crimes while 4,303 complaints suggest electoral violations.
The commission has also classified the complaints in four categories considering their potential to change the results. 8,794 complaints have been placed in A category.