Australian authorities say they've seized chemicals which could have been used to make 1 ton of methamphetamine and arrested four men in a joint operation with China.

Australian Federal Police said Wednesday they seized 1.4 tons of the precursor ephedrine, which could have been used to make meth with a street value of nearly 700 million Australian dollars ($500 million).

Investigators say they were tipped off by Chinese authorities about a syndicate suspected of importing commercial quantities of drugs into Melbourne.

Border authorities intercepted a container arriving from China labelled as ceramic tiles and glue but which police say contained 260 bags of ephedrine.

Police say they switched the ephedrine with an inert substance and delivered the consignment.

Two of those arrested are from Melbourne and two are Chinese nationals.