The debate about pill testing has resurfaced after two people died with three more critically ill after attending Defqon.1 on the weekend, a music festival in Western Sydney.

Last year's Spilt Milk festival was to be the first legal pill-testing trial in Australia, but the promoters sensationally pulled out of the trial six weeks out, because of issues around approvals.

Spilt Milk is at Commonwealth Park, land controlled by the National Capital Authority.

The Canberra Liberals wrote to federal ministers Fiona Nash and Greg Hunt asking them to intervene, given the Coalition government's anti-drug stance.

The pill-testing trial that eventually took place in Groovin the Moo in April was held at the University of Canberra, land controlled by the ACT government.

The service picked up two deadly substances - one that was responsible for the hospitalisation of 13 people in New Zealand a month earlier - and gave police and paramedics an idea what was circulating at the festival. None of the people who had their pills tested ended up in hospital or presenting for treatment.

Despite the success of that pilot, the National Capital Authority has told Fairfax Media it will not allow pill testing on Commonwealth land.

"The Commonwealth’s concern first and foremost is the safety, health and wellbeing of Australians, including the safety of people attending events held on national land," a spokeswoman said.

"The government does not support decisions to use illicit drugs, and does not in-principle support pill testing, as it could imply that illicit drugs are safe.

"All illicit drug use contains inherent risks and even taking a known substance can result in unintended harm. It is important to note that pill testing may not be able to identify all components in an illicit substance and does not take into account any underlying health conditions a person may have or interactions with any other substances or medications a person may have taken.

"Importantly, there is no legal framework currently in place and the Commonwealth will not facilitate measures to enable pill testing to take place on Commonwealth land, for the reasons I have mentioned."

This came as a shock to the STA-Safe Consortium, which ran the successful Groovin the Moo trial and had filed applications to test at more events across the ACT.

Canberra physician and consortium member Dr David Caldicott said the group was yet to be formally notified of any decision.

"If people want to decline applications it would be interesting to hear the reasoning. No doubt there's a strong reason for that to counter the benefits we saw from the last trial," Dr Caldicott said.

"To us where people can be harmed isn't dependant on whether it's Commonwealth or ACT land, people can be harmed everywhere.

"Whoever has responsibility for whatever type of land it is has a responsibility to ensure they're doing everything to reduce harm."

Dr Caldicott said there were inaccuracies in the authority's statement and he was happy to meet with bureaucrats and politicians to discuss pill testing.

"We are very aware of the current mood in the country and the clear support there is for pill testing," Dr Caldicott said. "We accept these sort of positions can frequently change, as can ministers."

Another member of the consortium, and Harm Reduction Australia president Gino Vumbaca, said the authority's position was "disappointing given what's happened on the weekend".

"We understand why people may be tentative or have concerns about pill testing. One of the misconceptions is it gives a green light to drug use. That's not what we do.

"What we're trying to do is inform people about what they're about to do, what the risks are and how we can mitigate those. If you provide people with information about the substance they're taking it tends to reduce drug use, not increase it. To brand pill testing as something that promotes drug use is untrue."

Pill testing was "not a panacea" but in the case of Groovin the Moo, it gave 128 people the chance to talk to medical professionals about their drug use for the first time, he said.

"Correct information provided by health professionals is something people would rarely argue is dangerous," Mr Vambuca said.

ACT Health Minister Meegan Fitzharris wrote to Mr Hunt last Friday, as his permission would be vital for the National Capital Authority to let pill testing happen at Spilt Milk.

"I urge you to take a strong stance on this issue as your leadership has the potential to save a life," Ms Fitzharris wrote.

An ACT government spokeswoman said the government was committed to providing a "supportive policy environment" for pill testing to be provided at this year's Spilt Milk.

"However, agreement between all relevant parties, including the National Capital Authority as the landowner, is necessary for a pill testing service to proceed at the Spilt Milk music festival," she said.

The ACT government saw pill testing as one component in harm reduction measures and was a "sensible approach to limiting the dangers of illicit drug use at ACT music festivals".

"This position in no way softens the ACT government’s stance on illegal drugs. The ACT government does not approve or condone illicit drug use. It is risky and dangerous to consume illicit drugs," she said.

However, ACT Opposition legal affairs spokesman Jeremy Hanson said it must be zero-tolerance.

"This is a matter for a coronial inquest and police investigation in NSW so I can’t comment further other than to say that it’s clear any level of drug use is dangerous and that’s the message to take out of this and we need to wait for the full review to occur to understand what’s gone wrong here. But fundamentally if you take these sort of substances you then put yourself at risk and I’d encourage people to be very cautious before doing that. Go to a music festival, have fun, you don’t need to take these drugs," Mr Hanson said.

NSW Premier Gladys Berejiklian has appointed a panel headed by NSW Police Commissioner Mick Fuller to investigate how to keep people safe at festivals but said she is categorically opposed to pill testing.

"It is quite shocking to me that in the last five years there have been four deaths at that festival," Ms Berejiklian said.

"Pill testing is not supported by the NSW government, I've been very clear on that point and I can't be clearer about that today.

"We can't turn a blind eye to illegal activity, we can't turn a blind eye to unsafe practices which are leading to death and injury."