The Sam Rainsy and Norodom Ranariddh parties called on the National Election Committee Monday to fairly investigate complaints following commune elections earlier this month.
The NEC must investigate complaints through April 23, but smaller parties say they see favoritism from the NEC toward the ruling Cambodian People's Party.
The Sam Rainsy and Norodom Ranariddh parties submitted more complaints than the rest of the twelve parties competing in the April 1 elections.
Keo Phalla, the head of NEC's dispute department, said the committee received more than 50 complaints from political parties, the majority from the opposition parties.
"The NEC is preparing to solve the issues of complaints according the law and regulations," Keo Phalla said. "Whatever it is, the NEC will do it according to the law stated for the communal election."
Official election results are scheduled to be released April 24.