Australian authorities have arrested members of outlaw motorcycle gangs in dawn raids on Tuesday following a 12-month investigation that seized 18 million Australian dollars worth of methamphetamine.

The arrests follow a joint operation with local and national authorities in Western Australia late last month where police located and seized 21 kilograms of the dangerous drug methamphetamine, commonly known as ICE.

The illegal drugs seized is a valued at 18 million Australian dollars (13.2 million U.S. dollars).

Authorities raided various properties in Brisbane, Queensland, simultaneously at dawn on Tuesday, seizing a further three kilograms of ICE, over 100,000 ecstasy pills, and 60,000 Australian dollars in cash.

Police also found a semi-automatic handgun, two sawn-off rifles and a semi-automatic rifle.

Police intercepted a vehicle at Tugun on Monday night and seized two kilograms of ICE.

A Queensland police spokesperson said those taken into custody are believed to be members of the Nomads and Comancheros Outlaw Motorcycle Gangs.

The 12-month operation evolved into a complex investigation after it was identified that a syndicate was allegedly trafficking ICE into other Australian states.