Harm Reduction Australia approached the ACT government with a plan for a drug-checking trial at next month's event, but this was knocked back after "careful consideration," an ACT government spokesman said.

Chief Minister Andrew Barr told ABC Radio on Friday the proposal had not been "well enough formed" to pursue at the May festival.

But ANU senior clinical lecturer and emergency physician Dr David Caldicott said the proposal had been based off a working model in the UK that tested 200 pills per festival and they had been in talks with the government since January about it.

"In fact it was so minutely detailed that the minister's office had the opportunity to ask 'what uniforms would those conducting the pill testing be wearing?' If there were issues they wanted to discuss they would quite easily have raised them'," Dr Caldicott said.

"Every question that has been asked of us as a research group has been answered so unless they were keeping questions in reserve I suspect there are no questions that remain unanswered."

ACT Greens leader Shane Rattenbury says he was "bitterly disappointed" his ACT government colleagues had passed up the opportunity.

Mr Rattenbury has just returned from the Netherlands, where he got to see a pill testing station in action.

"We're going to see nearly 15,000 young people turning up to a major music festival, these sorts of opportunities don't come along to often in Canberra," Mr Rattenbury said.

"In the background we've got a group of health experts, with the right equipment, ready to provide a service free of charge to government, we cannot afford to pass up these kinds of opportunities to roll out proven evidence-based harm minimisation measures."

Mr Barr told ABC Radio his government was not opposed to pill testing but had "a range of questions and concerns".

He also made clear the government would never "stamp your pill and say it's safe".

"I need to be clear, the government is never going to endorse the taking of illegal drugs but we also have responsibilities around harm minimisation," Mr Barr said.

"I consider this a health issue, not a law and order issue, but I do need to be clear that the government will not be endorsing the taking of illegal substances but we do recognise people do that and as much as we can provide support for other organisations. This needs to be an evidence-based, public health decision not a Facebook petition."

But Dr Caldicott said the evidence was already out there and government action would only be spurred on by tragedy.

"I think one of the greatest misconceptions about pill testing, particularly when it's conducted by medical folk, is that at any stage, is anyone ever encouraged to take a pill. In fact in the script which we read to the consumer, we advise them the only way to stay safe is not to consume their pill," Dr Caldicott said.

"We know 60 per cent, in some series 75 per cent, of people who are advised that their pill contains something other than what they were expecting do something other than consume that pill.

"I suspect the parents or the loved ones of the next overdose that could have been prevented by our initiative, they will be the ones doing the persuading."