The eldest son of Cambodia’s long-term ruler has been endorsed as the country’s next premier in a formality confirming the transition of power.

On Monday, Cambodia’s king issued a decree stating Hun Manet will succeed Hun Sen, who has ruled for 38 years.

Hun Sen announced he would step down just days after the 23 July election, which critics said was not democratic.

His party won all but five seats in parliament, after the main opposition was barred from the vote.

King Norodom Sihamoni issued the royal decree after Hun Sen sent a letter requesting the official note.

His appointment still needs to be confirmed by parliament on 22 August, but it is expected to sail through a National Assembly wher 120 of 125 seats are controlled by Hun Sen’s Cambodian People’s Party.

Hun Manet, 45, who until recently was the commander of the Royal Cambodian Army, has long been groomed for the leadership role.

His father first flagged a transition in 2021, but until July it was unclear when the handover would occur.

However Hun Sen announced that he would step down just three days after the election. He is one of the world’s longest-serving leaders, having ruled the Southeast Asian nation of 16 million people for nearly four decades.

He said at the time he was resigning to ensure stability in Cambodia.

However, Hun Sen said he would retain leadership of the ruling Cambodian People’s Party – a position political analysts say still gives him ultimate control.

Since he came to power following the fall of the Khmer Rouge regime four decades ago, Hun Sen’s rule has become increasingly authoritarian, dismantling opponents by jailing or exiling them.

On the weekend, in addition to marking his 71st birthday, Hun Sen confirmed the party’s landslide victory in the July election – polls which the US, EU and other Western nations have said was neither free nor fair.

The outgoing leader on Saturday also confirmed Hun Manet’s election as an MP for Phnom Penh, removing the remaining procedural obstacle for his ascent to power.

Hun Manet celebrated the result by posting a photo to Instagram showing his son presenting a bouquet of flowers to Hun Sen with the caption: “Happy birthday to respected and beloved father.”