A Japanese woman on death row for drug trafficking in Malaysia will appeal for a lesser punishment, her lawyer has said, through a recently enacted law allowing such prisoners to petition the country's highest court for sentence reduction.

Mariko Takeuchi, 49, lost her appeal at the Federal Court in 2015, which upheld lower court rulings in which the former nurse was sentenced to hang for trafficking 3.5 kilograms of methamphetamine into Malaysia in 2009.

The new law allowing prisoners sentenced to death or life imprisonment to seek reduced sentences, came into force Tuesday as part of the judicial reform that eliminated mandatory death sentencing for 11 serious offenses, including drug trafficking, murder and terrorism.

Takeuchi testified at trial that she did not know about the drugs found in a suitcase she brought to Kuala Lumpur International Airport from Dubai. She has pleaded innocent, maintaining that she was carrying the suitcase as a favor for an Iranian acquaintance.

Photo shows Mariko Takeuchi's suitcase alongside confiscated stimulants at a customs office near Kuala Lumpur International Airport on Nov. 4, 2009. (Kyodo)

The woman from Japan's Aomori Prefecture, who has been incarcerated since her arrest in 2009, is the first Japanese tried for drug trafficking in Malaysia and the first sentenced to death.

Although Malaysia still maintains capital punishment, judges have the discretion under the reformed system to review a sentence and mete out other forms of punishment to those who committed the serious crimes after examining court proceedings as well as grounds of the judgement.

Under the new law, Takeuchi could still face the death sentence for drug trafficking or a jail term of between 30 and 40 years, according to her lawyer.

Law minister Azalina Othman Said has said the law applies retrospectively so that prisoners on death row or facing life imprisonment can be given a chance to return to society and their families.

The Japanese woman's lawyer Hisyam Teh Poh Teik told Kyodo News on Monday his law firm has notified the court that it is ready to submit documents needed for the review of Takeuchi's sentence on her behalf.

According to government statistics, some 1,000 convicts including Takeuchi are currently on death row or jailed for life.