The woman, 38, was caught with 376 grams of the drug at Ho Chi Minh city's Tan Son Nhat airport in December last year, the Cong An Nhan Dan newspaper reported on its website.

She told the court she was planning to transport the drugs from Vietnam to Australia for a fee of $5,000.

The court in the southern Vietnamese city "sentenced her to 20 years' imprisonment for the charge of illegal transport of drugs", the Cong An Nhan Dan said.

Anyone found guilty of possessing more than 600 grams of heroin, or more than 20 kilos of opium, can face the death penalty.

Convictions and sentences are usually revealed only by local media, which is strictly under state control.

Vietnam has sentenced dozens of foreigners to death for drug offences — many of them Australian nationals of Vietnamese origin — but it has been decades since a foreign national was executed in the country.

The communist government also enforces compulsory "rehabilitation" programs for the country's estimated 140,000 drug addicts, which rights groups have strongly criticised, pointing to allegations of forced labour and abuse.

Despite the harsh sentencing, drug smuggling and use is still commonplace.

Agence France Presse - September 10, 2015