More than 700 kilograms of Xanax estimated to be worth $12 million has been discovered at a storage unit in Sydney’s south in what police have branded “the single largest seizure of pharmaceutical drugs in NSW history”.

Boxes of the anti-anxiety medication, officially known as Alprazolam, were discovered on Sunday night after Raptor squad officers executed a search warrant in Auburn, as part of an investigation into the interstate transportation of cash that police suspected was linked to criminal activity.

Police seized a total of 722 kilograms of the drugs. Photos supplied by police show the drugs to be stored in small bottles, each…