Police have charged 13 people after smashing a drug syndicate in south east Queensland.

More than 10 properties were searched yesterday and this morning at Gympie, Tin Can Bay, Southside, North Deep Creek and Veteran.

Detective Superintendent Steve Holahan from the Drug Squad says more than $600,000 worth of property, firearms and drugs were seized.

He says at one location a substantial amount of amphetamine was located.

Four women and nine men have been charged with more than 50 offences.

Charges include supplying, possession and trafficking of drugs.

They will appear in the Gympie Magistrates Court in the next month.

Police say more arrests are likely after the year-long investigation.