A 51 year-old Sydney mother of four faces the death penalty after allegedly carrying methamphetamine while in transit through Kuala Lumpur's international airport.

The woman was travelling from Shanghai to Melbourne on December 7 when she was searched by police and allegedly found to be carrying 1.5 kilograms of the drug known as "ice".

Under Malaysia's decades-long campaign against drugs, the woman faces death by hanging if found guilty of carrying more than 50 grams of methamphetamine.

Malaysian authorities have not released any details of the woman's arrest by customs officials at the airport.

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Authorities in Malaysia can hold a person for up to 14 days without charge.

The Australian high commission in Kuala Lumpur is providing consular assistance to the woman, who is believed not yet to have engaged a lawyer.

Western Australian truck driver Dominic Bird, 34, escaped the hangman's noose in Malaysia in July after a more than two-year legal battle following his arrest on drugs charges at a cafe near his Kuala Lumpur apartment in March 2012.

Malaysia's High Court ruled it would not appeal Mr Bird's earlier acquittal.

The prosecution's case against him fell apart amid allegations of police corruption, prompting calls for a moratorium on the death penalty in Malaysia.

The Sydney woman's arrest comes a week after two Australians were held in China on suspicion of smuggling a commercial quantity of the same drug in China.

Kalynda Davis, 22, has since returned home.

Her travelling companion, Peter Gardner, 25, was  born in New Zealand but has  lived in Sydney for many years and has dual nationality. He went to Richmond High School in Sydney's north-west, and worked for a local building company.

New Zealand's consul-general has visited Mr Gardner in a detention centre in Guangzhou and said he was being supported by his family and legal representatives.

It is not yet clear why Ms Davis was released while authorities continue to hold Mr Gardner.

More than 440 people have been hanged in Malaysia since 1960.

Two Australians, Kevin Barlow and Brian Chambers, were the first Westerners to be executed under the country's then new anti-drugs laws in 1986 after being arrested on the island of Penang with 141.9 grams of heroin.

Michael McAuliffe, another Australian, was hanged in Kuala Lumpur in 1993 after being found with heroin in his back pocket at a Penang airport security check-point.