Canberra, June 15 : The Australian Federal Police (AFP) on Thursday said that six men have been charged in connection with one of the biggest drug busts in the country's history. The AFP revealed they have also seized more than 6 tonnes of liquid and crystal methamphetamine imported to Australia from Canada in four separate shipments over five months, reports Xinhua news agency. Two men have been charged with attempting to import a commercial quantity of border-controlled drugs, if convicted, will face a maximum penalty of life imprisonment. Four more men, including a US national, have been charged with offences relating to trying to buy methamphetamine in Australia. It is estimated that the seized methamphetamine amounted to almost 19 million individual street deals with a total value of A$1.7 billion ($1.1 billion). The illicit drugs were found concealed in canola oil bottles bound for Victoria and New South Wales -- Australia's most populous states -- and replaced with harmless substances to give authorities time to identify offenders. Alison Money, AFP chief medical officer, said methamphetamine was highly addictive and had a significant physical, mental and social impact on users. "Every day, on average, 40 people are admitted to Australian hospitals from methamphetamine, heroin or cocaine use," Money said in a media release. "Every week, on average, 16 Australians die from heroin, amphetamine or cocaine overdose." /IANS