Australians are the world's biggest consumers of the drug ice, on a per capita basis, with most of the imported product coming from China, a Victorian inquiry has been told.

Up to 80 per cent of crystal methamphetamine brought into Australia comes from China, where the chemicals used to make it can be legally sourced, Australian Federal Police Detective Superintendent Matt Warren told Victoria's parliamentary inquiry into drug law reform on Monday.

Up to 80 per cent of the drug ice in Australia comes from China.

Since about 2010, Australian police have been seizing the finished drug, which is usually quite pure, instead of finding the precursor chemicals used for domestic manufacture.

"Simply because it's economically sensible for the criminal groups involved," Superintendent Warren said.