The unit executed eight search warrants last Wednesday, six in Narre Warren, one in Hampton Park and one in Hallam.

Detective Senior Constable Brian Whitehead said the haul consisted of about 1000 cannabis plants, with a total weight of about 1000 kilos. It was estimated to have a street value of about $500,000.

In addition to the cannabis, police seized complex hydroponic set-ups used to grow the plants.

Those arrested and charged include a Hampton Park man, 46, a Narre Warren man, 43, a Narre Warren man, 18, and a Hampton Park woman, 27.

They were charged with cultivating a commercial quantity of cannabis, trafficking a commercial quantity of cannabis, possessing a commercial quantity of cannabis and theft.

Senior Sergeant Phillip Ross said all four were remanded in custody after a hearing at the Melbourne Magistrates Court.

Police said they would consider applying to seize the houses involved as they were "used to commission an offence".

The houses, valued at about $2 million, could be forfeited to the state, Detective Senior Constable Whitehead said.