CANBERRA - A soldier has been killed and another has been seriously injured during a training exercise using live ammunition, defence officials have confirmed.

But the Australian Defence Department says it is too early to reveal what went wrong.

The soldiers were taking part in a night-time firing exercise about 9.30pm (CDT) yesterday at Cultana military base near Port Augusta in South Australia.

The dead soldier, from Sydney, was a member of the army's second commando regiment.

He died at the scene after being injured in a "training accident", the ADF said in a statement.

The second man, also from Sydney, was taken to Port Augusta for treatment and remained in a serious condition, it said.

"The events of last evening will be the subject of full civil and military investigations," army chief Ken Gillespie said on Wednesday.

"It is too early to make further comment with regards to the cause of this accident."

The exercise was specific training for an upcoming Afghanistan deployment.

Lieutenant General Gillespie has sent his condolences to the families, friends and colleagues of the soldiers involved.

The names and details of the two men would not be released at this time, he said.

SA police will head the investigation, supported by the Australian Defence Force's Investigative Service.