Cambodian authorities yesterday said that they will not investigate a bomb blast that killed two people – one of them an Australian – at a military base in Kampong Speu province on Thursday because the matter was a “private case”.

Two Australian men, whose names have not been released by Australian authorities, visited a private shooting range within the military base last week – a spot apparently frequented by tourists who shell out up to $300 to fire rocket launchers and other military weaponry.

One Australian and a Cambodian soldier, Koy Mok, 52, were killed, while fellow soldiers Sok Sarith, 48, Long Vuthy, 50, and another Australian man received minor injuries.

Australia’s Department of Defence on Friday confirmed the accident did not occur as part of a military training exercise and that the men were not Australian Defence Force personnel – despite the initial claims of the Cambodian military, police and provincial governor that they were bomb experts.

Defence Ministry spokesman Chhum Socheat said there would be no investigation as it was a “private case”.

“Inside the unit, they are good friends with [the Australians]. They allowed them to visit privately. It’s not an official case, and is not concerned with the military operation,” he said.

He added the Australians were well aware of the “risk [to] their life”, and hung up when asked if soldiers at the base would be reprimanded.

National Police spokesman Kirth Chantharith and Ministry of Interior spokesman Khieu Sopheak – who in the past has said such public shooting ranges on military bases are illegal – both said any investigation would be a matter for the military.

One of the survivors, Long Vuthy, said on Monday that he believed he was in fact getting demining training from Australian experts at the time of the tragedy.

“I thought it was my lucky day,” Vuthy said adding he hoped to learn skills from the Australians, whom he said had been there for two days.

Vuthy said he was sitting about 3 metres behind Mok and the Australian man – who were wiping earth from the bomb to determine its age and origin – when it detonated, killing them both.

“When they removed the earth, they also caused the detonation,” he said. “They believed the old grenade was OK.”

“When it exploded, I thought I was dead because of all the shrapnel and injuries all over my body. I did not know east from west, and the bleeding was like a pig’s neck being slit. I did not dare to remove my shirt to see the wound.”