SYDNEY: Australian law enforcement agencies discovered 1.26 billion Australian dollars ($900 million) worth of methylamphetamine hidden in imported boxes of silicon bra inserts and art supplies in the country's largest haul of the illicit drug in its liquid form, officials said Monday.

Four Hong Kong passport holders were arrested in Sydney last month over the import from China of 720 litres (190 gallons) of the drug, commonly known in Australia as ice, police said in a statement.

The liquid could have made about 500 kilograms (1,100 pounds) of high-grade crystal meth, Australian Federal Police Commander Chris Sheehan said.

Officials also seized 2 kilograms (4.4 pounds) of the crystalized form of the drug.

Justice Minister Michael Keenan said the operation used information gathered through new cooperation between Australian Federal Police and China's National Narcotics Control Commission. The Australian and Chinese agencies established a joint task force in November to investigate criminal syndicates trafficking methamphetamine.

"This largest seizure of liquid methylamphetamine to date is the result of organised criminals targeting the lucrative Australian ice market from offshore," Keenan told reporters.

The four will appear in a Sydney court next month charged with importing and manufacturing commercial quantities of illegal drugs. Each suspect faces a potential life sentence if convicted.

Keenan said the seizure was one the largest hauls of illicit drugs in Australian history.