Cambodian King Norodom Sihamoni on Monday presided over the opening session of the fifth legislature of the National Assembly, which was attended by only the ruling party's elected lawmakers as the opposition's elected legislators boycotted it.

Sixty-eight elected lawmakers from the ruling Cambodian People's Party (CPP) of long-serving Prime Minister Hun Sen were present at the opening session, while all the 55 legislators from the Cambodia National Rescue Party (CNRP) of long-time opposition leader Sam Rainsy did not attend.

Foreign diplomats were invited to the session. Among them are US Ambassador to Cambodia William E. Todd, Chinese Ambassador Bu Jianguo, and Japanese Ambassador Yuji Kumamaru.

Security has been tightened and anti-riot police have been deployed along streets in the city with barbed wire barricades being used to block roads surrounding key government's buildings, the Royal Palace, and the National Assembly.

"We have used thousands of security forces to ensure security and public order during the session," National Military Police spokesman Kheng Tito told Xinhua, adding that protests are not allowed during these days.

The opposition CNRP boycotted the session since it did not recognize the results of the July 28 parliamentary election, claiming serious vote fraud and demanding the formation of an independent poll probe committee, but the CPP rejected the request, saying the move was against the country's constitution and the election results were already ratified.

On Sunday, all the CNRP's elected lawmakers took an oath at the Angkor Wat temple in northwestern Siem Reap province, vowing not to join the parliament's opening session.

"We will not attend the opening session of parliament as long as there are no more talks with the ruling CPP in order to resolve the contested election results," CNRP's leader Sam Rainsy said.

Hun Sen and Sam Rainsy had held two rounds of talks last week, aiming at finding a way to break through the political impasse, but failed to reach any major agreement.

Hun Sen has said that his party has enough lawmakers to override any opposition parliamentary boycott and form a new government.

He said, according to the constitution, a new government would be formed by a 50 percent plus one majority, or 63 lawmakers, in the new parliament.

Hun Sen will govern the country for another five years through the election victory.

According to the official schedule, a new government led by Hun Sen will be formed on Tuesday.