The murder trial of a young Indonesian maid in Malaysia is adding new fuel to a bilateral row over the conditions faced by legions of migrant workers in the country.

Walfrida Soik is on trial in northern Kelantan state for allegedly killing her employer, a 60-year-old Chinese Malaysian woman who suffered from Parkinson's disease.

Soik is accused of stabbing the woman 42 times in 2010.

Her defence argues she was a minor at the time, lured by labour traffickers with false promises, whose employer abused her. She could face death.

The trial is keenly watched in Indonesia, where cases of abuse and exploitation prompted Jakarta to officially ban women taking domestic work in more affluent Malaysia in 2009 for more than two years.

Indonesian politicians have called for clemency, and its media have reported heart-wrenching stories about her.

"On the basis of humanity, we must save (Walfrida) from the death penalty," Anis Hidayah, executive director of Indonesian NGO Migrant Care, wrote on Change.org, where the group launched a petition signed 13,000 times.

"Indonesia and Malaysia must together make a commitment to protect women and children, and combat the crime of human trafficking."

Though the trial has been under way since 2012, Indonesian presidential candidate Prabowo Subianto elevated its profile recently by attending Malaysian court hearings including last month.

"If our legal team, our attorneys are optimistic, we hope for a good result," he was quoted by Indonesian media as saying.

An estimated two million Indonesians toil in plantation, construction, factory and domestic work -- both legally and illegally -- in Malaysia, which relies on poor foreigners to perform less appealing work.

Soik's lawyer Shafee Abdullah said a trafficker brought her from eastern Indonesia in 2010.

She was issued a passport Shafee said falsely claimed her to be 21 years old -- an adult at the time of the crime and eligible for the death penalty. Shafee said Soik is only now 21.

Promised "luxury and fun", she was abused, underfed and overworked, he said, causing "temporary insanity", which could spare her but mean time in a mental institution. A ruling could come next year.

Allegations of abuse against foreign labourers have included overwork, beatings, sexual abuse, even torture.

Malaysian authorities last year freed 95 Indonesians, among other foreigners, who were confined by a labour agent.

Malaysia has not commented significant on the diplomatically sensitive case, but Deputy Human Resources Minister Datuk Ismail Abd Muttalib has said the government is considering measures to "avoid the recurrence of criminal cases involving maids here".

Elsewhere, a Cambodian maid was starved to death in 2012 by her employers, earning them 24 years in jail. Cambodia had stopped sending maids a year earlier over abuses.

But poor Indonesian women have continued to arrive, many illegally.

"This is a situation where these agents are going all out to get domestic workers, particularly from remote villages, where the people tend to believe their promises," said Irene Fernandez, head of Malaysian migrant-labour rights organisation Tenaganita.

Malaysia has taken steps to improve maids' welfare, including requiring at least one day off per week and nearly doubling minimum monthly salaries to 700 ringgit ($220).

But activists say it is difficult to enforce such requirements.

The Indonesian embassy estimates 400,000 women work in Malaysia as maids -- about half illegally. Indonesian workers, legal and illegal, account for roughly half of all foreign labourers.

Paradoxically, the two Muslim neighbours' closer scrutiny of the issue has slowed processing of legal maids, causing a shortage and fuelling the efforts of traffickers bringing in illegals, activists said.

Jeffrey Foo, president of the Malaysian Association of Foreign Housemaid Agencies, said households are frustrated by long waits and high fees charged by some opportunistic agents.

"I believe the demand is still there but many Malaysian employers are already demoralised. We need the mechanism to be more smooth," he said.

Meanwhile, the lure for many poor young women continues.

Mini, a 28-year-old who has worked in Malaysia eight years and would not give her full name, said she was "scared" to come due to the country's reputation.

"But I think it's okay. The salary is higher than in my country. I'm very happy I can help my family."