An alleged Chinese drug syndicate operating in Sydney has been dismantled and two men arrested after authorities raided 10 homes across the city's south-west this week and allegedly seized more than 300 kilograms of the precursor drug ephedrine.

Police say the seized drugs, the biggest haul of its kind in Australian Border Force (ABF) history, could be used to manufacture 240 kilograms of the drug ice, with an estimated street value of $240 million.

The drugs were concealed in items posted from China and Hong Kong to Sydney, police say. Credit:NSW Police

The drugs were allegedly hidden in items including car radiators, coolers, aluminium rods and wall hangings.

The items were sent from China and Hong Kong to properties in Sydney's south-west over the past year, police say.