KING Norodom Sihamoni will preside over the inauguration and swearing in of the new National Assembly, government officials say, despite continued threats by the opposition to boycott the ceremony.

"The National Assembly will hold its first meeting soon and the King will preside over the ceremony," Leng Penglong, secretary general of the National Assembly, said in a statement. The swearing-in is expected to take place September 24.

But Yim Sovann, a Sam Rainsy Party lawmaker and member of the National Assembly's permanent standing committee, said his party and the Human Rights Party (HRP) would still boycott the ceremony if their complaints over voter fraud in the July 27 general election were not taken seriously by the National Election Committee.

Both parties say that hundreds of thousands of names were intentionally left off voter registration lists, stopping many opposition supporters from casting their ballots in an election dominated by the ruling Cambodian People's Party.

"The two opposition parties are not interested in attending the inauguration ceremony of the National Assembly and we hope that there will be some change from now until September 24, otherwise it will affect the formation of the new government," Yim Sovann said.

Government officials have warned that any opposition lawmakers refusing to take part in the Assembly's first session out of protest could face losing their seats.

Preliminary poll results show a strong swing to the CPP, which won 58 percent of the vote over the SRP (21.9 percent) and the Human Rights Party (6.6 percent).

The NEC is reviewing opposition complaints before the announcement of official election results on September 17.