Immigrants arrested at NSW cannabis house

Four people including three illegal immigrants have been arrested after police discovered more than 120 cannabis plants in a home in Sydney's south.

The hydroponic set-up was uncovered when officers raided the Riverwood home on Wednesday afternoon and police said the "enhanced cultivation" crop had an estimated potential value of $248,000.

A 34-year-old man was arrested and will appear in Sutherland Local Court on Thursday, charged with cultivating a prohibited plant.

Three other men, aged 21, 24 and 25, were detained as suspected illegal immigrants and police said their inquiries into the incident were continuing.