A Northern drug taskforce raided eight properties in Northern Tasmania on Friday April 13, allegedly seizing guns, drugs, cash and stolen jewellery.

On the same day Victorian police raided an alleged clandestine Methylamphetamine drug in Sunbury, an outer suburb of Melbourne.

Five people, including two Tasmanians, were arrested and charged with drug manufacture and trafficking.

Eleven more people were arrested and charged with drug trafficking and other offences in Tasmania.

Detective Inspector Scott Flude, who oversaw Operation Dizzy from the Launceston CIB headquarters, said police investigations were continuing but the bulk of the suspected offenders had now been charged.

The raids seized 500 grams of methylamphetamine, with a street value of between $2 million and $4 million.

Also seized was 30 kilograms of cannabis, valued at $500,000; 42 firearms, some of which had been reported stolen as far back as 2001; a $400,000 boat; $330,000 in cash; $80,000 in jewellery allegedly stolen from Launceston's Haab Jewellers in June last year; and 68 abalone.

The haul was laid on a table in Launceston police headquarters this morning.

Detective Inspector Flude said it was a sophisticated operation, and the biggest seizure of drugs and firearms he had seen in his time in CIB.

Assistant commissioner Donna Adams said the operation was a credit to the hard work of the Northern drug taskforce and sent a clear message to anyone trying to set up an organised crime operation in Tasmania.

"You will be targeted and we will disrupt your operations,'' Ms Adams said.

Ms Adams said the investigation had uncovered links to existing organised crime networks but not to any bikie gangs.

She alleged the methylamphetamine had been trafficked between Tasmania and other states by being carried on domestic airline flights, and said one offender had been arrested at Launceston Airport as they headed on to a flight to Sydney.