PHNOM PENH: Cambodia's new parliament convened on Monday (Aug 21), setting the stage for long-time ruler Hun Sen to officially hand power to his eldest son after last month's one-sided election. Hun Sen's Cambodian People's Party (CPP) won all but five of 125 seats in the lower house in July polls that were widely decried as a sham after the main opposition party was barred from running. ADVERTISEMENT Days after the landslide victory, Hun Sen - one of the world's longest-serving leaders - announced he was stepping down and handing power to his eldest son, Hun Manet, after nearly four decades of rule. Cambodian head of state King Norodom Sihamoni - who holds a largely symbolic role - opened parliament and congratulated the newly elected MPs including Hun Sen and Hun Manet, both wearing traditional attire. He said the country had made great progress over the last 30 years, and urged MPs to make "further efforts to help people live with equality". The king also said he believed the new government will receive parliament's mandate. Parliament will reconvene on Tuesday to officially elect four-star general Hun Manet, 45, as the country's new leader. ADVERTISEMENT Earlier this month, Hun Sen unveiled the new Cambodian government headed by Hun Manet, and which also includes his youngest son Hun Many and his nephew in senior roles. Related: Cambodia's Hun Sen unveils new government with son Hun Manet as leader Hun Sen heir could get New York business reception after Cambodia succession Commentary: Cambodia’s next leader Hun Manet presents a new era for the country’s global relations Hun Many will become the minister of civil service, while the sons of the current interior and defence ministers will take over their fathers' posts, according to a draft list of the new cabinet members seen by AFP. The outgoing PM's nephew, Neth Savoeun, currently the powerful national police chief, will be a deputy prime minister. Several children of Hun Sen's allies are also set to take top jobs in the new government. Former Khmer Rouge cadre Hun Sen, who has ruled since 1985, rejected international condemnation that last month's polls were unfair. ADVERTISEMENT He said the handover was done to avoid "bloodshed" should he die in office. Rights groups accuse him of using the legal system to crush any opposition to his rule, jailing scores of activists. After stepping down, Hun Sen will become president of the Senate early next year and act as head of state when the king is overseas. He has said he will continue serving in other positions until at least 2033.