A committee controlled by Cambodia's ruling party has ruled that 28 opposition lawmakers should be expelled from the National Assembly ahead of elections next month because their parties merged into a new party.

Ruling Cambodian People's Party lawmaker Cheam Yeap said Thursday that 25 legislators from the former Sam Rainsy Party and three from the former Human Rights Party lost their right to sit in the assembly because they quit their old parties to join the new Cambodia National Rescue Party.

The Cambodia Daily newspaper quoted Cambodia National Rescue Party President Sam Rainsy as saying the move was illegal and the assembly would lack a quorum if the expulsions were carried out.

All 12 members of the committee that oversees the assembly's daily operations belong to Prime Minister Hun Sen's ruling party.