Tran Thi Hong Loan, a 33-year-old Australian of Vietnamese origin who lives in NSW, was convicted of trafficking 580 grams of heroin and given a 20-year sentence at a one-day trial on Friday, a court official said.

Vietnamese authorities found the heroin hidden on her body and in her luggage as she was about to board a flight to Sydney last August, said the official, who identified himself only as Hieu.

She has 15 days to appeal her sentence.

In Vietnam, possessing, trading or trafficking 600 grams of heroin or 20 kilograms of opium is punishable by death or life in prison.

About 100 people are sentenced to death each year in Vietnam for drug-related offences.