SYDNEY - A US national is facing life imprisonment after police allegedly found 17 kg of methamphetamine in her luggage upon arrival at Sydney Airport.

The Australian Federal Police (AFP) and Australian Border Force (ABF) said on Friday that the 50-year-old woman approached airline staff asking for help to find her lost luggage upon arrival in Sydney from San Francisco on Thursday.

At the same time, airline staff found a suitcase marked with the woman's surname in the baggage claims area and referred it to ABF officers. Officers searched the luggage and allegedly found vacuum-sealed bags containing a white crystalline substance concealed in packing cubes.

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Subsequent testing of the substance returned a positive result for methamphetamine, with the weight estimated at 17 kg.

The matter was referred to the AFP who arrested the woman and charged her with one count of importing a commercial quantity of a border-controlled drug.

If convicted, she faces a maximum penalty of life imprisonment.

"ABF officers work closely with not only our law enforcement partners, but also airline crew and other airport staff, to identify and intercept potential threats," ABF Superintendent Elke West said in a statement.

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"This is a timely reminder to passengers entering Australia, the Australian Border Force and our partners are always on the lookout for suspicious passenger behavior. If you attempt to import illicit drugs into this country, you will be stopped in your tracks."

The suitcase as well as a phone and other personal belongings were seized by the AFP for forensic testing.