Five men in Australia's Victoria state capital Melbourne have been charged in a crackdown on a major drug syndicate that also netted items ranging from luxury vehicles to a golden gun, authorities said on Thursday.

The suspects, including four Australians, were arrested in the past week after police investigations identified the syndicate based in the city's western suburbs, the federal police said in a statement.

Police seized drugs including 4.175 kg of methamphetamine and 2.5 kg of heroin, as well as cannabis-growing facilities, firearms, a Lamborghini sports car and other luxury vehicles as part of about 12 million Australian dollars (8.7 million U.S. dollars) of assets.

The drugs have an estimated street value of more than 4 million Australian dollars (2.9 million U.S. dollars), police said.

"This operation sends a clear message to those seeking to wreak havoc on our community with life-threatening illicit drugs. Not only could you spend your life behind bars, all your belongings including your house, car, and anything else used in the commission of a crime, or bought with the proceeds of crime, can be seized to satisfy Australia's proceeds of crime and confiscation regime," said Commander Amanda Kates from the federal police.

The men have been charged with offenses including trafficking a commercial quantity of a controlled drug, which carries a maximum penalty of life imprisonment. Investigations are ongoing and additional arrests are expected, said police.