Sydney shooting
The underground drug den was made up of three shipping containers transformed into a single roomDavid Gray/Reuters

Police have rescued an 8-year-old boy who for weeks was locked in an underground drug den in Australia. Three adults have been charged with kidnapping and accused of cultivating large quantities of hydroponic cannabis for commercial use at the property in Elands town, about 300km north of Sydney.

According to Newcastle Herald, police began the investigation fearing for the safety of the boy who they found had often skipped school. In November, police visited the property and found no evidence of mistreatment towards the boy. But they found tracks of cannabis cultivation and last week received a go-ahead to raid the property.

"The door to the small room in the shed was locked from the outside and police will allege that the boy was mistreated and only allowed out of the shed for chores and sometimes food,'' detective inspector Peter McKenna said.

Police have seized cannabis worth $500,000 (£335,965). They also found the 8-year-old boy's three siblings, aged between 1 and 9 years. The raid was conducted on 19 December.

All four children have been placed in the custody of NSW Family and Community Services. "We're very thankful we got there when we did and that those children are now having the proper care that they need," McKenna said.

The underground drug den was made up of three shipping containers transformed into a single room. "It was actually located underneath a deck that was built against the house, and through a remote control switch actually moved along hydraulically, revealing two large trap doors," McKenna said. "You went down a ladder, into a tunnel into what we would say is a very sophisticated set-up with lights and about 225 cannabis plants located there."

Police are on the hunt for two more individuals who were residing at the property. "To complete our investigation we will be looking to speak to both of those adults," McKenna said.