CANBERRA - Criminals are getting increasingly creative in producing crystal methamphetamine, the United Nations (UN) has warned.

According to a report from the UN Office on Drugs and Crime (UNODC), seizures of crystal methamphetamine - also known as ice - across Asia indicated that producers are shifting to diverse chemicals to manufacture the addictive drug rather than the common ephedrine and pseudoephedrine.

The report said that the new chemicals "suggest increased sophistication among illicit manufacturing facilities."

Jeremy Douglas, the UNODC regional representative for southeast Asia and the Pacific, said that producers were more proficient than previously thought.

"The crime groups are using increasingly diverse sets of chemicals and increasingly diverse chemical sources, meaning from different countries," he said.

"If they can't get their hands on one chemical, they're getting their hands on other chemicals and then getting creative in terms of how they produce the meth.

"Pseudoephedrine seizures aren't being made at all, even though there are indications that it is still in use," he said. "What we're seeing is diversity in chemicals, including some very unique chemicals pushing into the region. It's alarming because that indicates it is going to be even harder, given they're using potentially non-controlled chemicals."

The 2019 National Drug Strategy Household Survey, which was published by the Australian Institute of Health and Welfare (AIHW) in October, found that 5.8 percent of Australians over the age of 14 - or 1.2 million people - had used methamphetamine.