The two Australians involved in a deadly explosion at a shooting range in Cambodia were tourists and not part of an official Australian military training operation as claimed by Cambodian authorities, according to various sources.

Key points: Australian man in 40s killed in shooting range explosion, another injured

Australian man in 40s killed in shooting range explosion, another injured Cambodian authorities claimed pair were "military trainers", not tourists

Cambodian authorities claimed pair were "military trainers", not tourists Australian Defence Department confirmed no personnel involved

The blast happened around 1:30pm on Thursday (local time), killing an Australian man in his 40s and a Cambodian in his 50s.

Another Australian was injured, along with two Cambodians.

Cambodian police, the provincial governor and a government spokesman described the Australians involved as military trainers.

However, the ABC understands there was no official military training scheduled for the area and the men were likely tourists visiting a shooting range run by the Cambodian military for profit.

"It's a cover-up by the RCAFF (Royal Cambodian Armed Forces)", said a source with knowledge of the incident.

The Department of Defence confirmed the accident did not occur as part of a military training exercise and no ADF personnel were involved.

Soldiers at the Kampong Speu Armoured Headquarters told the ABC they were ordered not to speak to media because allowing foreigners onto the range to fire weapons was "illegal".

The range is well-known among tourists who pay cash to shoot AK-47 assault rifles and rocket-propelled grenades (RPGs) and to throw hand grenades.

Sorry, this video has expired A man, not a victim in the explosion, fires a weapon at the shooting range in Cambodia.

Similar shooting ranges exist near Phnom Penh airport and in Siem Reap.

The outdoor range in Kampong Speu is used for heavier weapons, with promotional videos showing tourists firing RPGs at propane tanks to create fiery explosions.

Initial reports on the explosion described the Australians as military trainers.

However, a one-page written report in Khmer from the head of the tank unit on which the shooting range is located suggested the men had no formal role.

"The Australian nationals told them [two Cambodians] they were experts at mine clearance," wrote Lieutenant General Lanh Kao, the commanding officer at the tank base.

"They went together to visit the real shooting range [and] when they arrived there, the Australian nationals saw many types of unexploded ordnance (UXO)," Lieutenant General Lanh Kao said in the report seen by the ABC.

"At that time he picked up the UXO and it exploded in his hand, causing serious injuries to two people and slight injuries to three others."

"They were all sent to the Kampong Speu referral hospital but because of the serious injuries, two people died," Lieutenant General Lanh Kao said.

A screenshot of the range's website showing men, not the victims of the explosion, firing AK-47s. The website has since been taken down. ( www.cambodiafr.com )

No military rank noted for Australian men

A police report on Thursday attempted to identify the Australians, however there may have been problems with the translation of Khmer language.

The ABC understands both Australians involved were men in their 40s.

The police report did mention the military rank for at least one of the Cambodians involved, but no military ranks were noted for the two Australians.

Police based their initial report on interviews with surviving Cambodian military personnel but later told the ABC the military was not cooperating with their investigation.

"If the military tell us a lie, what can we do?" a senior police officer said.

The Australian Defence Department referred media inquiries to the Department of Foreign Affairs and Trade.

"The Department of Foreign Affairs and Trade is providing consular assistance to the family of an Australian man killed in Kampong Speu Province and to an Australian man injured in the same province, in accordance with the Consular Services Charter," the department said.

"Due to privacy obligations we are unable to provide further information."