Police said a “complex drug trafficking syndicate” operating in southeast Queensland had more than 25 drug couriers linked to a 35-year-old Upper Mount Gravatt man supplying methylamphetamine.

The syndicate allegedly sold $50m worth of drugs in one year, but detectives also seized 18kg of meth, two firearms, cocaine, ketamine and about $556,000 in cash over their 14-month investigation.

Last month, detectives found about six kilograms of methylamphetamine, $330,000 cash, a commercial money counter, cocaine and a mobile device during the search of a vehicle allegedly used by the syndicate.

Two weeks later detectives executed a search warrant at an area of bushland near Kholo, northwest of Brisbane.

Police allegedly located a demountable used to produce illicit drugs, as well as about 12kg of methylamphetamine.

A 61-year-old man was charged with a string of drug-related offences, including trafficking, possessing dangerous drugs and receiving or possessing property obtained from trafficking.

Five other people between the ages of 28 and 40 have all been charged with similar drug-related offences.

All have faced the Brisbane Magistrates Court and will appear again later in February and March.

Detective Senior Sergeant Ken Rogers applauded the investigators involved in Operation Tango Balboa.

“I commend the diligent efforts of all involved in this substantial operation, whose results have caused major disruption to the supply of dangerous drugs across southeast Queensland through the collapsing of a significant drug syndicate,” he said.

“There are many people before the courts that, should they be found guilty, are facing potentially lengthy jail terms, some in excess of 20 years.”