Police have stumbled upon a home drug lab after being pranked by a little girl, south of Sydney.

The five-year-old dialled Triple Zero on Monday night before hanging up the phone without saying anything.

Officers traced the call to a home on Elm Street at Albion Park Rail, south of Wollongong, and conducted a welfare check on the property.

Just after midnight on Tuesday, police knocked on the door of the home but got no answer.

They noticed a light on in the garage and entered the property, allegedly finding 15 hydroponic cannabis plants.

A 30-year-old woman was arrested at the scene and has since been charged with growing the drug plants and will face court next month.