A five-member bench chaired by Chief Justice Tengku Maimun Tuan Mat ruled that the conviction was unsafe.

Maria Elvira Pinto Exposto was arrested at KLIA in December 2014 with 1.1kg of crystal methamphetamine stitched into the lining of a bag given to her by a man in Shanghai.

Tengku Maimun said Exposto was proven to have had no knowledge of the drugs and was an innocent carrier.

Exposto, who remained calm throughout the hearing, was represented by Muhammad Shafee Abdullah while deputy public prosecutor Tetralina Ahmed Fauzi prosecuted.

She was found not guilty in December 2017 by the High Court in Shah Alam, which accepted the argument by the defence that she did not know the bag contained drugs.

However, the ruling was overturned the following year by the Court of Appeal which sentenced her to death.

Exposto maintained that she did not know about the stash of drugs, also known as ice.

She said she had been fooled into carrying the bag after travelling to China to see a person called “Captain Daniel Smith” whom she had met online.

After engaging in an online romance, Exposto travelled to Shanghai to see Smith, who claimed to be a US serviceman.

However, she was given the bag by a stranger who asked her to take it to Melbourne.

The drugs were discovered at KLIA when she voluntarily offered her bags for customs inspection.

Under the Dangerous Drugs Act, anyone caught with at least 50g of crystal methamphetamine is considered a trafficker and is subject to the death penalty.

Two Australians were hanged in Malaysia in 1986 for heroin trafficking – the first Westerners to be executed in the country – in a case that strained relations between the two countries.