Aussie soldier may have had drug overdose

An Australian soldier is in a serious condition after a suspected drug overdose at his base in Tarin Kowt in Afghanistan.

"It would appear at this early stage that the use of illicit drugs may be involved in this incident," Australian Defence Force head Air Chief Marshal Angus Houston told reporters.

"He remains in a serious condition in an unconscious state and is being closely monitored by medical staff."

The experienced commando, who was discovered in his room last Friday, is being treated at a military hospital in Germany.

Air Chief Marshal Houston said a commission of inquiry would be established to determine the circumstances surrounding the incident.

The inquiry will also examine the effectiveness of the ADF's prohibited substance testing program and investigate the extent of the use of drugs by those in the field.

A civilian with judicial experience would be appointed to head up the inquiry.

Air Chief Marshal Houston said materials found in the soldier's room suggested drugs were involved in the incident.

"I can tell you that while the investigation is ongoing and no findings are yet available a bottle of pills and separately white powder thought to be an opiate were found in the soldier's room," he said.

"However, I stress to you that analysis and medical testing to confirm the exact nature of the substance and whether it may have caused or contributed to his condition is ongoing."

The other members of the soldier's unit were being tested for the use of illicit drugs.

"My thoughts and prayers are with the soldier and his family during this very difficult time," Air Chief Marshal Houston said.

The soldier, who was not identified, was deployed in Afghanistan with the Special Operations Taskgroup. Air Chief Marshal Houston said his prognosis for recovery remained "uncertain".

"His family have asked for privacy at this time and I ask everybody to respect that," he said.

The ADF has a zero-tolerance policy regarding the use of illicit drugs.