One of the world’s deadliest drugs has been discovered inside Australia’s borders for the first time.

Australian Border Force officials recently detected a package containing carfentanil in a Sydney mail centre, The Daily Telegraph reports.

Carfentanil is a synthetic drug commonly used to sedate elephants and animals of similar size.

It’s an analog of fentanyl, a synthetic drug used in heart surgery, but is far more powerful and thus makes it easier to overdose on in smaller amounts.

Officers warn that a single gram of carfentanil is enough to kill 50,000 people.

Drugs like fentanyl and W-18 have sparked concern in Australia over the past few years, amid a new wave of deadly painkillers emerging across the world.

But carfentanil is far more dangerous.

In an interview with news.com.au, Adjunct Research Fellow with the National Drug Research Institute Stephen Bright warned the drug was already showing up on streets in the United States.

“We’re seeing carfentanil being sold in the US,” Dr Bright said. “That’s 100 times stronger than fentanyl — and that’s a fact. It’s used on animals. It’s used to take down elephants. The amount of the reversal agent required for humans is six times that of a heroin overdose.”

ABF NSW regional commander Tim Fitzgerald likewise stressed its dangers are not to be underestimated.

“Carfentanil can be fatal to humans in incredibly small doses, and is toxic when injected, ingested, inhaled, or even if it comes in contact with unprotected skin and eyes,” he told The Daily Telegraph.

Australian Border Force Regional Commander Tim Fitzgerald says carfentanil can be fatal in tiny doses.Source:News Corp Australia

Dr Bright said one of the biggest dangers of such drugs is that people don’t actually know what they’re taking, which can greatly increase the risk of an overdose if luck isn’t on your side.

“If you go back 20 years, everything was more clear — heroin was heroin, MDMA was MDMA, and so on,” he said.

“The situation now is we have thousands of these new drugs that are being sold as traditional drugs. Heroin could be fentanyl. Heroin could be W-18. It could be U44770. We don’t know.”

It is believed that such drugs are created in Chinese labs, where less-common drugs are mass-produced and sold online as ‘traditional’ drugs.

The drug will then be illegally exported overseas to Mexico, where cartel-linked drug operations will dilute it with everything from heroin to baby powder before distributing it north to the US.

Given they are typically manufactured in homemade drug labs, the contents and potency of the final “product” will vary from batch to batch.

But because it’s so potent, it’s easier to smuggle than other drugs in a compact size.

This potency also makes such drugs more marketable. Its strength means a lower dosage is required, therefore it’s more profitable to sell.

Mr Fitzgerald said the ABF is working closely with domestic and international law enforcement agencies to prevent the importation of these substances.