Australian police have announced the country's largest-ever seizure of drugs worth 1.26 billion Australian dollars ($900m, £620m). Four Hong Kong nationals have been charged with alleged involvement in smuggling 720 litres (190 gallons) of methylamphetamine, commonly known as ice or crystal meth, in gel bra inserts.

The accused, who were arrested in Sydney last month, could face life imprisonment if convicted for their crimes, police said. About 500kg of high-grade crystal meth could have been made from the seized liquid methylamphetamine, police said.

"This largest seizure of liquid methylamphetamine to date is the result of organized criminals targeting the lucrative Australian ice market from offshore," New South Wales (NSW) Justice Minister Michael Keenan told reporters in Sydney.

"This has resulted in 3.6 million individual hits of ice being taken off our streets with a street value of $1.26bn. This has been a very good day for Australia law enforcement and a very bad day for the organised criminals that have targeting the Australian drug market," Keenan said. He added the drugs were smuggled into Australia from an organised crime syndicate operating out of China.

According to police, the operation to nab the culprits began last December when the Australian Border Force found 190 litres of liquid methamphetamine hidden inside a shipping container which had arrived from Hong Kong with boxes that contained gel bra inserts.

After the discovery of the drugs, the Australian Federal Police, the NSW Police, the Australian Border Force, the Australian Crime Commission and the NSW Crime Commission carried out a joint operation and found an additional 530 litres of liquid methamphetamine concealed inside art supplies housed in five storage units in Sydney in the suburbs of Miranda, Hurstville, Padstow and Kingsgrove.

Usage of crystal meth by Australians is one of the highest in the world, the Australian Crime Commission had said in March 2015.

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