ADF Figures show almost 600 Diggers have been caught taking illegal drugs in the past five years despite top-brass attempts to dismiss reports of drug problems in the Australian Defence Force.

ADF figures provided to The Sunday Telegraph revealed 589 serving soldiers, sailors and airmen tested positive to taking illicit drugs since 2005, The Sunday Telegraph reports.

The results were released after news an Australian soldier was found unconscious from a suspected drug overdose in his barracks at Tarin Kowt in Afghanistan.

Private Daniel Landt-Isley remains in a serious condition in a US military hospital in Germany. Investigators found a bottle of pills and white powder – thought to be an opiate – in the soldier’s room.

In November, The Sunday Telegraph revealed Diggers were using marijuana, cocaine, heroin and other hard drugs on tours of duty and were returning to Australia as addicts

The scandal is a major embarrassment for ADF chief Angus Houston, who said drugs the story was “completely baseless”.

Last week, Air Chief Marshal Houston was forced to order all 300 members of Australia’s Special Operations Task Group in Afghanistan to be drug tested.

Afghanistan produces 93 per cent of the world’s heroin, which experts claim can be accessed easily and cheaply.

Regular drug tests were conducted between June, 2005 and April, 2010 on 44,000 ADF personnel, a spokesman said.

The ADF refuses to detail the types of drugs involved in the positive tests or to give any breakdown of how many involved soldiers serving overseas.

Military culture expert Dr Ben Wadham said drug use was a traditional issue for defence force personnel and put the use down to stress and military culture.

“Soldiers traditionally work hard, but they also play hard and that has been characterised by copious amounts of drugs and alcohol,” Dr Wadham said.

“But it’s also the stresses they have to endure in highly risky work situations, which can drive them to take drugs.”

He said drug habits had also changed over time.

“In the 1990s cannabis was the drug of choice but in the second half of the decade, pills, amphetamines and steroids became more prevalent. In the 2000′s it is still largely pills, cocaine and steroids while there has traditionally been problems with opiates in Afghanistan.”

He said heroin came very cheap in Afghanistan.

“They traditionally get it through contact with US soldiers, wandering through opiate regions or through a connection with local sellers who often sell drugs to soldiers to undermine their ability on the battlefield.”

Soldiers told The Sunday Telegraph, on the condition of anonymity, that drug use by serving soldiers was still prevalent.

One soldier, who served in Iraq two years ago, reported that “a big selection” of steroids was available when he spent time on an American base.

“Most guys were on it because there’s so much pressure on you to be at peak physical performance that people turn to steroids just to keep up,” he said.

An ADF spokesman said the drug test result figures compared favourably with that recorded for the civilian community.