Importers who deal in medicines derived from endangered wildlife are being targeted as part of a worldwide crackdown on the trade.

Police, customs and specialised units are targeting thousands of illegal traditional medicines smuggled in by plane, boat and mail - mainly arriving from China and Hong Kong, 3 News reported.

Many of the imports contain animals and plants from endangered species such as tigers, bear and turtles, according to One News.

The operation, headed by Interpol, has now netted about $20 million worth of illegal substances in 18 countries.

MAF and Customs said border control agencies now knew what to look for and warned importers to beware.