Camden detectives are investigating the discovery of 394 cannabis plants uncovered during a house fire in Tahmoor this week.

Fire brigade crews discovered the plants when they were called to the York Street property at 8.30pm on Monday, after neighbours noticed the home was filled with smoke.

A fire brigade spokesperson said an electrical fault in the hydroponic lights set-up in the roof of the house was the likely cause of the fire.

Police have also said the fire appeared to have caused a power surge or decline to the surrounding premises, with a number of residents reporting their electrical appliances were flickering during the incident.

Bowral Police Inspector Jim Cody said police found "several hundred cannabis plants at various stages of maturity" during their initial police inspections after the fire was put out.

Police have searched the premises for the last three days and found a total of 394 plants, as well as seizing a variety of drug paraphernalia.

Inspector Cody said the house appeared to be part of a "extensive hydroponic set-up" that had been operating for some time.

"We believe this cannabis operation may have been operating at this premises for at least six months," he said.

"From a residential point of view this is the biggest haul of cannabis plants within this local area command at a residence in recent memory."

"It's quite uncommon to have such an elaborate cannabis set-up in a residence, it was obviously part of a major dealing operation."

Police are still determining the estimated value of the drugs seized due to the various sizes of the plants found.

The plants have been taken away for analysis and destruction.