Four people have been arrested in Melbourne and a large stash of precursor drugs seized, capable of making ice with an estimated street value of $690 million.

The arrests and seizure of 1.3 tonnes of ephedrine came after federal police were tipped off by Chinese authorities about a syndicate suspected of importing commercial quantities of drugs into Melbourne.

Australian Federal Police estimate the seized ephedrine has the potential to make 922 kilograms of ice, with a street value of about $691.5 million, equating to more than 9.2 million street deals of ice.