SYDNEY • The Australian and US authorities announced that they had seized around a billion dollars worth of methamphetamine - or Ice - in a bust that revealed new ties between Mexican cartels and Aussie biker gangs.

The Australian Federal Police said on Friday that a joint investigation led the United States Immigration and Customs Enforcement to uncover 1.7 tonnes of drugs in California last month.

The US authorities said the illicit cargo - with a street value of A$1.29 billion (S$1.24 billion) - was hidden in two shipping containers carrying audio equipment bound for Australia.

After a series of raids this month, two US nationals and four Australians were arrested last week in the Melbourne and Sydney areas. They face various charges, including attempting to import illegal drugs, and face maximum sentences of life in prison in Australia if convicted.

The investigation appeared to reveal cooperation between Mexican cartels and Australian biker gangs, developing what the authorities say is a worrying new vector for drugs to arrive to Australia.

Assistant Commissioner Bruce Hill of the Australian Federal Police said: "This is a serious warning. We now believe the Mexican cartels are actively targeting Australia. They have been sending smaller amounts over the years. This is now flagging their intent. Australia is now being targeted."

He added, without naming the cartel involved: "The cartel is one of the most powerful and violent drug trafficking syndicates in the world."

He also pointed to high Australian street prices and prevalent drug use as a "drawcard" for organised crime.

Colombian and Mexican cartels have long looked to local partners to open new markets for their produce and shift legal risk.

Australian police indicated that the country's biker gangs, with deep involvement in organised crime, were willing interlocutors.

AGENCE FRANCE-PRESSE