Ve Thi Tran was arrested at Phnom Penh airport last January by immigration police after they received a tip from the Australian Federal Police.

The 38-year-old was about to board a flight to Hong Kong, bound for Australia as her final destination.

The municipal court found her guilty of drug trafficking after she had been held in Phnom Penh's notorious Prey Sar prison for more than a year.

"The court has decided to sentence Ve Thi Tran to 30 years in jail and fines her 80 million riel ($19,700)," said Judge Khuon Sona.

The Vietnamese-born Australian admitted to the court on April 9 she carried the bags of heroin, which she received from two Vietnamese men in Phnom Penh.

She had stashed the bags in the lining of her luggage, according to state media.

Cambodia has taken a hard line on drugs in recent years in response to smugglers turning to the country as a transit point, particularly for heroin and methamphetamine.

Heavy sentences are passed down for drug trafficking, with hundreds arrested including senior officials and foreigners.