The Constitutional Council on Thursday upheld the denial of a complaint by the Human Rights Party over alleged voting-list irregularities throughout Cambodia in July's election.
The Human Rights Party had claimed in its complaint to the National Election Committee that 15,255 polling stations were found with registries containing voter names twice.
The double names could have led to ineligible voting, the party said in its complaint.
The NEC rejected the complaint, and that decision was maintained by the Council.
Thursday's hearing was the final decision of the Constitutional Council over election complaints that were filed by the Sam Rainsy and Human Rights parties.
Nhiek Vannara, deputy secretary-general of the Human Rights Party and the legal representative in the case, told reporters Thursday the Council's decision was "very unjust for the Cambodian voters and the Human Rights Party."
"We cannot accept the result of the decision," he said. "But we have no place to continue to complain. We are very, very sorry for the Constitutional Council members, in this unjust decision, but we hope that we will stand up for justice for the next election."
Nhiek Vannara called the decision "artificial."
He told the hearing the double names could have led to an estimated 1 million voting irregularities.
NEC legal representative Em Sophath said during the hearing the denial of the HRP complaint was "very legal and fair."
"The Human Rights Party complaint did not have enough evidence to support [it]," Em Sophath said.