Under the new rules, the party that wins the second-largest number of votes will still be allocated seats even if it fails to pass the 7 percent threshold normally needed to get seats.
Several opposition parties say the changes do not go far enough to instill fully functional democratic processes and warned that they would boycott the next parliamentary elections if the change is approved.
They have called for the threshold for entry into parliament to be lowered to no more than 3 percent and that representatives from all parties participating should have members on the electoral commission.
The amendments require presidential approval, which is expected.
