Customs officials say an international crime syndicate is using Sydney high school students as drug mules, with two teenagers already facing possible charges.
Officers from the Australian Customs and Border Protection Service are contacting parents and principals at three schools in the city's inner-west amid revelations students have been paid to accept packages from China.
The teenagers are contacted via social media or at their school itself and asked to pass on their home address in return for a few hundred dollars.
Two students, aged 15 and 16, are facing possible charges and others are being interviewed, with both public and private school pupils being targeted.
Customs regional director for New South Wales, Tim Fitzgerald, says the parcels' contents appear innocuous at first.
"They've got general goods inside them, in some instances like motorbike helmets, LED lights and shoes, and within those goods are concealed precursors such as ephedrine," he said.
Mr Fitzgerald has compared those involved with the drug syndicate to vultures.
"This does take it to a new low. They are involving students that are innocent," he said.
"The promises that the syndicate gives these students in a lot of instances is [that] because of their age they won't be held legally responsible and that's completely incorrect.
"There are 25 years' imprisonment but there's other consequences for activities such as this for kids as well. It can impact on uni applications, future jobs, even travel overseas."
Customs says one of the parcels intercepted contained four kilograms of ephedrine, enough to make about $250,000 worth of the street drug methamphetamine.
NSW Police Commissioner Andrew Scipione says it is not clear how widespread the tactic is but it is disturbing.
"What I do know is this is a grubby business. The low life that would try to get your young people and our young people into this type of crime should be totally condemned," he said.
"Someone who gets caught up in this as a young person could throw away their future, throw away their life.
"This is a very very serious matter. These organised criminals don't care about your children. They don't care about anyone other than themselves and making money.
"We need to again today call on parents to know what your young people are doing. Know what packages are arriving at the house."
Customs officers, with the help of NSW Police, raided five addresses earlier this month.