Scientists have sniffed out three new recreational drugs at Australia's only fixed pill testing site.

The party drugs have similar effects to MDMA, also known as ecstasy, and ketamine, which is used as a medical anaesthetic.

They were discovered by a team of scientists at the Australian National University at the CanTEST site in Canberra.

Professor Malcolm McLeod, who made the discoveries, says it's not yet known how dangerous the new drugs are.

"We don't know how it will affect people or what the health consequences are," Professor McLeod said.

"While derivatives of these stimulants first emerged in New Zealand in the early 2000s, we actually don't know a lot about them," he said of the ketamine-like substance.

One of the samples, which the would-be user thought was a stimulant with similar effects to amphetamines, also included methamphetamine and MDMA.

The testing site also discovered a new ketamine-like drug in October 2022, which had not been seen in Australia before.

It has analysed more than 1700 samples since opening in July 2022.

One in ten samples are thrown out after the person learnt what was in the drug.

Scientists triggered a health alert in late 2022 after discovering a potentially lethal opioid in pills that were falsely sold as oxycodone.

The new discoveries come amid a wider debate in Australia about pill testing in other states after several people overdosed at summer music festivals.

Advocates have acknowledged that while testing is not a panacea, it greatly increases harm minimisation with people discarding potentially lethal substances.