Updated

Cambodia's parliament convened despite a boycott by the opposition, as the country is gripped by political crisis following disputed elections that led to mass protests and violence.

King Norodom Sihamoni opened the session -- the first since the July polls won by strongman Hun Sen -- and urged the country to "stand united", as parliament was surrounded by heavy security.

No opposition MPs were present at the meeting after vowing a boycott over their demands for an independent investigation into the election.

According to official results of the July poll, the ruling Cambodian People's Party (CPP) won 68 seats against 55 for the Cambodia National Rescue Party (CNRP) but the opposition has rejected the tally, alleging widespread vote irregularities.

Dissatisfaction with the election saw three days of demonstrations earlier this month, which descended into violence when a protester was shot dead as security forces clashed with a stone-throwing crowd.

Security has been stepped up around official buildings in recent days, with anti-riot police and road blocks near parliament in the capital Phnom Penh.

Hun Sen, who suffered his worst poll result in 15 years, agreed to find a peaceful solution to the dispute in talks with rival Sam Rainsy but he has rejected opposition CNRP calls for an independent probe.

The Cambodian strongman is likely to be sworn in for another five-year term on Tuesday.

The opposition, which held a ceremony on Saturday for its MPs to swear not to attend Monday's parliament meeting, said it had not changed its demands.

CNRP spokesman Yim Sovann told AFP that the legislature was "undemocratic" to have opened with only ruling party members.

Cambodia's king urged lawmakers to work towards social justice and good governance in his speech to parliament.

"The Cambodian nation must stand united and show the highest national solidarity on the basis of the implementation of the principles of democracy and rule of law," he said.

The political crisis saw a new twist on Friday when a pro-opposition Cambodian prince -- the king's cousin -- went on hunger strike in protest at Hun Sen's contested win, demanding "justice for voters".

His protest ended after military police expelled him from the pagoda where he was holding the hunger strike.

Hun Sen, 61, a former Khmer Rouge cadre who defected and oversaw Cambodia's rise from the ashes of war, has already ruled for nearly three decades but has vowed to rule until he is 74.

Garment exports and tourism have brought buoyant economic growth but Cambodia remains one of the world's poorest countries and the government is regularly accused of ignoring human rights and suppressing political dissent.