Twenty-four opposition lawmakers boycotted a ceremony Tuesday where National Assembly members were giving themselves medals.
The medals were to be issued to each lawmaker for "positive work" during the past legislative session. The next legislative session will not take place until after July's general election.
Opposition leader Sam Rainsy said his party "did not want to receive this kind of medal, because such medals are nonsense and valueless.
"Contrarily, I think that it is a shame for those who wear these medals," he said. "It is not an honor, because, in general, those who receive the medal are especially tainted, people with illegal businesses, and we do not want to compare ourselves with those people."
The party recommended in a statement that the National Assembly use its time to strengthen its capacity in order to improve social and moral values, through passing an anti-corruption law and pushing the government to apply responsibility for the national interest.
Lawmaker Chiem Yeap, of the ruling Cambodian People's Party, said the opposition's attitude, posting the statement and boycotting the ceremony, was in contempt of the king.
"The king signed the royal decree allowing the medal, via a proposal of the National Assembly medal committee," said Chiem Yeap, who is a deputy in the committee.
The SRP said in its statement the medal was given to several people, including foreign and Cambodian businessmen, as well as officials, and among them were "good people" and "criminals," like drug traffickers, smugglers, illegal loggers and land grabbers.
The medal did not represent merit, the statement said, but money and power.
Tuesday's medal ceremony came at the end of this five-year legislative term.
New lawmakers will meet again after the elections. The National Assembly failed again this session to pass a much-anticipated anti-corruption law.