Human Rights Party Presdient Kem Sokha on Tuesday called for competing political parties to help ensure proper ballot counting after Sunday's election.
"If we do not collaborate in protecting ballots from fraud… the ballots of the people who want to change [the government] leaders will be cheated," Kem Sokha warned.
Kem Sokha told reporters Tuesday he was appealing for all parties to cooperate following reports that the ruling Cambodian People's Party was seeking to buy or threaten observers from other political parties.
CPP National Assembly Vice President Nguon Nhel said the ruling party has never bought or threatened observers from any parties or other group.
Sam Rainsy Party officials could not be reached for comment.
Norodom Ranariddh Party and Funcinpec senior officials said their parties supported the appeal.
Over the past two weeks, Funcinpec has met quietly with officials the opposition and other competing parties to discuss the protection of ballot fraud, Funcinpec Secretary-General Nhiek Bunnchhay said.
In 1998 and 2003 election, the Sam Rainsy Party accused the National Election Committee of cheating the ballots to serve the Cambodian's People Party.
NEC Secretary-General Tep Nitha denied such allegations.
"Since previous elections, there was not any evidence showing ballot fraud," he said. "There was only accusations against the NEC."
The NEC works to ensure fair ballot-counting by counting in front of observers and political party members at each ballot station, he said. Following the local count, the NEC will count the ballots and declare the results the day after the election.
More than 90,000 NEC officials will work at the 15,255 ballot stations across the country, while more than 24,000 observers are expected to work the election.
More than 62,000 political party observers will also join, he said, including 20,000 from the CPP, 6,000 from the Sam Rainsy Party and 7,600 from the Human Rights Party.