A Canberra corrections officer, former prisoners and health experts are warning of a looming HIV epidemic in Australia's prisons.

It comes as 40 per cent of inmates at a correctional centre in Canberra tested positive to Hepatitis C as part of a voluntary testing program undertaken in August.

One Canberra corrections officer says there are more dirty needles within the Canberra prison now than ever before.

But the union which represents prison officers remains strongly against a proposed trial prison needle exchange program in Canberra.

The ACT Government is expected to make a decision about the trial by the end of the year.

Sterile single-use injecting kits are freely available to drug users in the community, but not inside Australian prisons.

A 32-year-old former inmate of Canberra's Alexander Maconochie Centre told the ABC she witnessed illicit needles being shared between inmates.

"They are just a normal syringe but they are cut down very short. Small enough so they can be packaged but big enough so they can be used," she said.

"People hide them in their bodies you know, like I suppose their body, anywhere."

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Her partner is still inside. She is looking forward to his release later this month but is also concerned for his health and hers.

"There's Hep C as it is and soon enough it will be AIDS and once AIDS hits in there what are they going to do?" she said.

Alex Wodak heads the Alcohol and Drug Service based at St Vincent's Hospital in Sydney, and he says roughly 25 per cent of Australia's prison population are injecting drugs.

Dr Wodak is concerned about the risk of an HIV explosion in Australia originating in prisons.

"Were Australia to have an epidemic of HIV beginning among people who inject drugs, it is almost certain that it would begin in one of our prisons. So we are very exposed to this risk," he said.

Getting worse

Some prison officers say the situation is worse in the national capital.

Paul Cubitt currently works part-time at the Alexander Maconochie Centre and he has over a decade of experience in a range of prisons and drug rehabilitation centres around the country.

He heads up Law Enforcement Against Prohibition (LEAP) Australia, a group representing 300 people with law enforcement experience that is calling for an end to all drug prohibition.

Mr Cubitt says he has never seen so many syringes in a jail.

He acknowledges he is among a minority of corrections staff who support the proposed trial.

"Under a controlled regime it will actually take those needles that currently exist within a correctional centre out of the environment, and prisoners will be more willing to use a clean item under a level of anonymity which then protects them and protects staff," he said.

The union which represents more than 10,000 public prison officers remains strongly against the proposed ACT prison needle exchange trial.

The Community and Public Sector Union 's national secretary, Nadine Flood, agrees action must be taken to curb prisoner drug use, but says other paths should be explored before trialling a needle exchange program.

Prison needle exchange programs have been operating overseas for over a decade. Ten countries provide inmates with clean needles.

Dr Wodak says it is shameful Australian prisons are lagging behind.

"When you look around the world there haven't been any of the disaster stories that people have been claiming, guaranteeing would happen," he said.

"The sky hasn't fallen in, there are really no serious negatives that we should be worried about."