South Australian police uncovered more than $6 million of dried cannabis and plants across 19 homes in a major cannabis seizure.

After criminal investigations by South Australia police, a major drug raid was carried out against an international drug syndicate and their Adelaide cells.

There were a total of 642 cannabis plants, 61kg of dried material, $29, 000 cash and one vehicle seized by South Australian police.

Sophisticated hydroponic operations were found in 12 of the 19 raided properties, with no evidence of anyone living in any of them. All properties had their electricity meters bypassed to avoid detection.

Three men aged 37, 39 and 40 were arrested and charged with various drug-related charges including cultivating a commercial quantity of cannabis, trafficking, theft of electricity and money laundering. It is suspected that the drugs were being circulated around the country, with money being sent to European institutions.