Australian police have seized what they believe is more than A$1 billion worth of methamphetamine, more commonly known in Australia as "ice" and elsewhere as "crystal meth." It has been discovered in huge shipments of silicon bra inserts.

The 720-litre haul, which has been described by police as the largest ever seizure of liquid methamphetamine (also known as methylamphetamine) in Australian history, is part of a months-long operation in which the Australian Federal Police (AFP) were monitoring an importation ring based out of Asia.

Four people have been charged since Jan. 15, police announced Monday, with importing the drug in bra inserts and art supplies from China to Australia. The Joint Organised Crime Group operation began in November, and tracked multiple shipments of ice entering the country.

Image: Getty Images

In late December, 530 litres of liquid meth and 2 kilograms of crystal meth were found in the art supplies being stored in four Sydney suburbs. On Dec. 26, police examined a delivery from Hong Kong and discovered a further 190 litres of liquid meth in thousands of silicon bra inserts.

On Jan. 14, the police conducted a controlled delivery of the drugs to a warehouse in Sydney and arrested a 33-year-old Chinese national. On Jan. 25, police discovered a drug manufacturing operation, linked to the liquid meth discovery, at two Sydney residences and arrested three more people: a 59-year-old Chinese man, a 37-year-old man from Hong Kong and a 52-year-old female from Hong Kong. All involved face a maximum penalty of life in prison.

Australian Crime Commission NSW State Manager Warren Gray said in a statement such operations help curb the influx of drugs such as ice into Australia. "The ACC has assessed that methylamphetamine poses — by far — the greatest threat to the Australian public of all illicit drug types, and by a significant margin," he said.

Detective Chief Superintendent Ken Finch reiterated his comments. "Our squad works 365 days a year to combat transnational organised crime," he said. "The dedication of our detectives and the members of our partner agencies has seen four people being placed before the courts and ensured these dangerous drugs did not reach the streets of Sydney."

Image: Getty Images

The AFP have been questioned over their valuing of meth, with reports earlier valuations put the price of the drug per kilogram at a much lower amount. ABC News reported last month the AFP valued a haul of the drug at approximately $666,000 per kilogram, in comparison to $2.5 million per kilogram in this operation.

Here are 2 x @AFPmedia busts from January where ice was valued at $666,000 a kilo: https://t.co/s3etG2oj1V and https://t.co/115SwHVAEH ..1/2 — Lucy Carter (@lucethoughts) February 15, 2016

"A decision was made to standardise AFP drug calculations from the most current Illicit Drug Data Report (using the upper range figure) as previously it was mid-point and state by state based. Now we use a single point of reference," the AFP said in a statement on Monday afternoon.

Much has been written of the "ice epidemic" in Australia, after former Prime Minister Tony Abbott announced a task force in 2015 to deal with what he believed was an alarming situation.

"Ice is far more addictive than any other illicit drug. It does far more damage than any other illicit drug," he said in April. "The propensity for violence, the propensity to subsequent, very serious mental illness, the propensity to disfigurement which ice produces means that this is a drug epidemic way beyond anything that we have seen before now." In 2015, an article in The Conversation stated that "while Australia certainly has a problem with ice, it’s hardly an epidemic."

Nicole Lee, an associate professor at the National Centre for Education and Training on Addiction at Flinders University, wrote that methamphetamine has become more pure and economical, and there has been an increase in people seeking treatment. Most statistical increases, though, are related to regular users increasing their use of the drug, she said.

"While investment in policing and prevention is important, the bulk of the changes in use and the resulting harms are due to the small proportion who use more regularly and are at risk of dependence," she said.

The 2015 report, The Australian methylamphetamine market: The national picture, also showed the use of meth has been consistent since 2010 — 2% of respondents had used ice in the last 12 months — with a change in the frequency of use and an increase in the type of methamphetamine from powder to crystal form.

It states, though, that crystal meth "poses the highest risk to the Australian community and is of significant national concern" due to "a considerable increase in the number and weight of detections at the Australian border" since 2010.

Others believe this is due to an increased police focus, rather than an increased threat to the public and have called for more to be done for the treatment and support options for those addicted to ice.