Two Malaysian nationals have been charged after authorities allegedly caught them unpacking more than 1.2 tonnes of a precursor chemical used to make the drug ice inside a south-west Sydney warehouse.

Australian Border Force officers allegedly detected the 1.2 tonnes of ephedrine inside a large shipment of home furniture from the port of Shenzhen, China, during an X-ray examination at the Sydney Container Examination facility on Tuesday.

Authorities show off the alleged ephedrine seizure. Credit:Australian Border Force

Ephedrine is commonly used by illicit drug manufacturers to make methamphetamine or ice. The amount seized was capable of producing a tonne of ice, equal to 10 million hits, with a street value of $750 million.

Malaysian nationals Weng Kay Chong, 22, and Min Yok Cheaw, 63, were arrested in a commercial warehouse in Roselands shortly before midnight on Monday.