Thailand's Constitutional Court announced on Wednesday that it will deliver its verdict on August 29 whether to oust Prime Minister Paetongtarn Shinawatra over her handling of a diplomatic spat with Cambodia.

A group of conservative senators filed a case accusing Paetongtarn of unprofessional conduct and breaching ministerial ethics during a border row with Cambodia that led to the two neighbours' bloodiest military clashes in decades.

Paetongtarn, daughter of billionaire ex-PM Thaksin Shinawatra, took office less than a year ago when her predecessor was kicked out of office by the same court.

Suspended from her duties by the court last month, the 38-year-old has defended her actions, insisting she acted in the country's interests.

In a leaked phone recording, Paetongtarn addressed Cambodian statesman Hun Sen as "uncle" during a call about the tensions and referred to a Thai military commander as her "opponent" – remarks that sparked a backlash.

Conservative lawmakers accuse her of kowtowing to Cambodia and undermining the military, and allege she breached constitutional provisions requiring "evident integrity" and "ethical standards" among ministers.

Paetongtarn could become the third Shinwatra to be ousted early as premier, after her father and aunt Yingluck – both thrown out in military coups. (AFP)