Cambodia's parliament in 2006 approved a law that would require all Cambodians aged 18 to 30 to serve in the military for 18 months, although it has never been enforced.

Relations with neighbouring Thailand have been tense since May, when a long-standing territorial dispute boiled over into cross-border clashes, killing one Cambodian soldier.

"This episode of confrontation is a lesson for us and is an opportunity for us to review, assess, and set our targets to reform our military," Hun Manet said.

"From 2026, the military conscription law will be implemented," he told a ceremony at the Royal Gendarmerie Training Centre in central Kampong Chhnang province.

Hun Manet said the service period would be extended from the 18 months outlined in the legislation passed two decades ago to 24 months, and pledged to "look at increasing" Cambodia's defence budget.

"Our national defence, the building of our military, is not to invade anybody's territory but it is to protect our territory," he added.

The Cambodian soldier was killed by Thai troops in a firefight in a disputed area known as the Emerald Triangle, where the borders of both countries and Laos meet.

The incident soured relations between Phnom Penh and Bangkok -- causing the closure of border crossings as Cambodia banned fuel and gas imports from Thailand.

It also caused a domestic political crisis in Thailand, where Prime Minister Paetongtarn Shinawatra has been suspended from office pending an ethics probe over her conduct during the row.

A diplomatic call between Paeotongtarn and Hun Manet's father, former leader Hun Sen, was leaked from the Cambodian side, sparking a judicial investigation.

Neighbouring Thailand already has military conscription for young and able-bodied men, who enter a lottery to determine whether they have to serve.