SYDNEY - Australian authorities have charged a US national with a major drug importation offense after allegedly finding 20 kilograms of cocaine in her luggage at Sydney Airport.

The 31-year-old US citizen was intercepted for a baggage examination on arrival in Sydney from Los Angeles on Sunday, the Australian Federal Police (AFP) and Australian Border Force (ABF) said in a joint statement on Monday night.

ABF officers conducting the examination allegedly found 14 black vacuum-sealed bags filled with 20 kg of a substance that testing identified as cocaine.

The AFP arrested the woman and seized the drugs, which had an estimated value of A$6.5 million ($4.2 million).

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She has been charged with one count of importing a commercial quantity of a border-controlled drug. The offense carries a maximum penalty of life imprisonment.

"People considering smuggling drugs through our airports need to think about the consequences of their actions. If caught, you will face losing some of the best years of your life sitting in a prison cell," AFP Superintendent Morgen Blunden said.

He said that the seized volume of cocaine could have equated to 100,000 street-level deals.