Cannabis worth £3.5m was seized by 130 police officers in early morning raids across south Wales and the west of England today.
Eight arrests were made by police and £400,000 in cash was discovered in the crackdown operation.
A large cannabis factory was later found and destroyed by authorities in Cardiff, and further raids were made in Newport, Bath and Bristol.
Detective Inspector Paul Latham, who led the operation, said: "Operation Pristina was put in place to target individuals believed to be involved in the cultivation and supply of cannabis across South Wales and the west of England.
"During the course of this operation we have successfully disrupted many of those who have been suspected of dealing in drugs."