China and Cambodia began a joint military exercise in the Kampong Speu province
The Phnom Penh Post newspaper quoted Defence Ministry spokesman Chhum Socheat as saying there would be no investigation as it was a "private case".
The Phnom Penh Post quoted Kampong Speu Governor Vy Samnang as saying that Prime Minister Hun Sen had offered his condolences to Malcolm Turnbull in Sydney on Friday morning, where both were attending the ASEAN summit.
However, the Prime Minister's office declined to confirm that Hun Sen offered condolences.
Just days after the deadly explosion on the Armoured Headquarters base in Kampong Speu, China and Cambodia began a joint military exercise in the province.