Police are on the look-out for two more individuals after the emergence of a "heinous" drug bust involving at least one child being locked up at a property near Taree, on the NSW mid-north coast.

Key points: Elaborate hydroponic cannabis growing set-up discovered near Taree

Elaborate hydroponic cannabis growing set-up discovered near Taree Eight-year-old child who had allegedly been locked up taken into care

Eight-year-old child who had allegedly been locked up taken into care Three other children also taken into care

Three other children also taken into care Three adults arrested and charged

On Friday, police said they uncovered an elaborate hydroponic cannabis growing set-up beneath a working spa bath, operated via a hydraulics system, at a remote property at Elands.

Three adults have been arrested and charged.

Police also "stumbled on" four children aged between 12 months and nine years old.

One of the children had allegedly been locked in a shed for long periods over the past few weeks.

The children were placed in the care of New South Wales Family and Community Services after officers from the Child Protection Unit travelled to Elands from Port Macquarie.

Police told the ABC it was a "shocking" case.

"That side of the investigation is being handled by our child abuse squad," Detective Chief Inspector Peter McKenna said.

"We're very thankful we got there when we did and that those children are now having the proper care that they need."

A spokesperson for NSW Family and Community Services (FACS) said it was "deeply saddened to hear of the story involving the young boy".

"FACS is working with police to assist with their investigation and can confirm the child is now safe."



Officers carrying out a drugs raid at a property in Elands allegedly found a hydroponic cannabis set-up as well as four children, who were put into care. ( NSW Police )

Drugs hidden underneath deck, accessible by spa bath trap door

Police told the ABC they received intelligence there was cannabis being cultivated, and on arrival found a highly sophisticated operation.

They allege more than 200 plants were found in the subterranean chamber.

"We found an elaborate hydroponic set-up there," Detective Chief Inspector McKenna said.

"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.

"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 said there were three buried shipping containers welded together to make the space.

Police allege that the entrance to an underground cannabis set -up was revealed by the pressing of a switch. ( NSW Police )

"There was actually a spa bath, a working spa bath sunken into the deck in the middle of the deck, so the whole thing just slid across revealing these trap doors," Detective Chief Inspector McKenna said.

"I think the offenders there were more surprised than us that we actually found it.

"We were prepared to find drugs and in fact cannabis plants being grown there.

"We believed there may well have been some type of hidden set-up, it's not unusual.

"But this is one of the most sophisticated ones we have ever seen, the way they have gone about it to hide the drugs the way they did."

Police seeking two more adults in relation to investigation

A 28-year-old man, a 26-year-old woman and a 19-year-old man arrested during the raid appeared in the Taree Local Court at the weekend and were refused bail.

Detective Chief Inspector McKenna said police still wanted to speak to two more people.

"Our investigations have revealed there were two other adults who were residing at the property at Elands. To complete our investigation we will be looking to speak to both of those adults," he said.

The trio in custody have been charged with cultivating a large commercial quantity of a prohibited drug.

The woman is facing a separate charge of detaining a person with intent for financial advantage.

The case will be heard again on February 2.