Detective Acting Sergeant Elissa Smith, of the Warrnambool police crime investigation unit, said eight search warrants were executed in Warrnambool and two in Hamilton on Thursday and Friday, resulting in eight people being arrested.

She said the arrests were part of Operation Abalone which investigators started in September last year.

The warrants were executed at properties in Warrnambool's Kagoola Avenue, Dales Road, Landy Grove and Cleveland Street.

Two Hamilton properties were also raided on Thursday and another two on the eastern side of Warrnambool on Friday.

Acting Sergeant Smith said quantities of methamphetamine, cannabis, GHB, MDMA, cocaine and ketamine were seized from the properties.

She said the drugs were yet to be weighed but one property alone uncovered one ounce of methamphetamine - more than nine times the trafficable amount.

A number of vehicles and a motorbike, which were either stolen or believed to have been purchased with the proceeds of crime, have also been seized.

Two women and six males aged between 19 and 30 have been arrested and are facing a number of serious charges, including conspiracy to traffick drugs of dependence.

Acting Sergeant Smith said a business and residential address in central Warrnambool was also raided on Thursday and a 30-year-old man was arrested and charged with possessing a silencer and possessing proceeds of crime. He was released on bail.

Senior Sergeant Chris Asenjo said police had spent several months investigating "drug trafficking involving a criminal network".

"This has been a very significant and protracted investigation utilising the full resources of Victoria Police," he said.

"On Thursday we made the decision to pull the trigger and resolve it and we've managed to disrupt what we say is a major drug trafficking network operating across south-west Victoria and south-eastern South Australia."

Senior Sergeant Asenjo said it was a good outcome for the community.

"Any opportunity to disrupt criminal networks moving significant quantities of drugs is a huge win for the community," he said.

"Drugs cause a great deal of hardship for people addicted to them and their families.

"There are flow-on effects with people addicted to drugs turning to crime or trafficking drugs to feed their addictions."

Senior Sergeant Asenjo said he believed there would be more arrests made in the coming days and weeks.

He said police would continue to target drug traffickers operating in the south-west.

"We won't rest on our laurels because we know there are other people there to pick up the pieces," Senior Sergeant Asenjo said.

Have you signed up to The Standard's daily newsletter and breaking news emails? You can register below and make sure you are up to date with everything that's happening in the south-west.