Three people remain in hospital after a mass drug overdose at the Electric Parade Festival in Melbourne on the weekend.
Twenty-one people were taken to hospital on Saturday after suspected overdoses at the festival, with authorities believing many of those ill took the drug GHB.
Eighteen people have reportedly been released from hospital, while three people are still receiving treatment.
Forty people were arrested at the festival for a range of offences including drug supply. One man was detained by police, allegedly carrying ecstasy, cocaine, MDMA, LSD, ketamine and hash.
Assistant Police Commissioner Stephen Leane will reportedly meet with organisers of the festival to discuss whether they should be allowed to host future events in the wake of the overdoses.
Royal Melbourne Hospital head of emergency Professor George Braitberg told NewsCorp Australia that the many hospitalisations could have been caused by a derivative of GHB, known as GBL.
GHB is a liquid form of ecstasy and GBL is said to have a slower release time, which can prompt users to double down on their doses.
The incident showed the need for authorities to introduce pill testing at festivals, Greens leader Richard Di Natale said.
"We must get to a point in this country where we acknowledge that what we're doing at the moment is not working, its not preventing people from taking drugs, far from it," Di Natale told the ABC.
"What it does do is it encourages people to take harmful substances when there are interventions out there that could prevent it."
The Greens have repeatedly called for the introduction of pill testing, which it has likened to the legal injecting room in Sydney's Kings Cross and the city's successful needle exchange program. The party argues that both programs support safe drug use and don't promote drug taking.
The alarming incident comes just days after Queensland police warned that a new highly toxic and potentially lethal drug known as carfentanyl had hit the state's streets.
"I am advised that carfentanyl is a highly toxic and potent synthetic based drug, with a 0.002mg dose enough to kill a person," Police Minister Mark Ryan said.
"The fact that this illegal drug has been located in Queensland is very concerning and together with the police, we are urging people to not take any risks at all with this illicit drug."
Queensland police warn the drug is 10,000 times stronger than morphine and should not to be used for recreational purposes.
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