Cambodia's prime minister has sought to revise a voting law ahead of next month's general election, a move apparently aimed at quelling boycotts as the ruling party's opponents are all locked out from running.

The bill bars anyone who fails to cast ballots from running in future elections, and imposes fines on people who prevent eligible citizens from voting. The bill's backers claim that it is aimed at ensuring elections can be conducted without any disruptions.

But the bill comes after the main opposition Candlelight Party was excluded from the upcoming election. The National Election Committee disqualified the party last month, claiming that it failed to submit the necessary documents. Some opposition supporters have been calling for a boycott of next month's vote.

Prime Minister Hun Sen said on Monday that the country's lower house would deliberate and pass the bill by the end of this week.

In the previous election in 2018, his ruling People's Party claimed all 125 seats in the assembly, while the largest opposition party was forced to disband.

The United Nations human rights office expressed concern about the bill.

Its spokesperson Jeremy Laurence said, "Such an amendment, if enacted, would constitute an overbroad restriction on the right to freedom of expression and a breach of the right of all citizens to stand for election."

The UN office urged the Cambodian government to change course, and act swiftly, to enable a free and fair election.