KUALA LUMPUR - Amnesty International on Wednesday urged Malaysia to end appalling treatment of migrant workers, saying many were raped, abused and unpaid and endured conditions "close to bonded labour".

In a damning report, the human rights group accused the Malaysian government of "facilitating" human trafficking after it found cases of immigration officials delivering Myanmar detainees to gangs on the Thai border.

Malaysia is one of Asia's largest importers of labour, with a workforce of 2.2 million, but Amnesty said they were too often "lured" to Malaysia and "used in forced labour or exploited in other ways".

"Migrants, many from Bangladesh, Indonesia and Nepal, are forced to work in hazardous situations, often against their will, and toil for 12 hours a day or more," the group said in a statement.

"Many are subject to verbal, physical and sexual abuse," it added.

Amnesty said most workers borrowed substantial sums to pay recruitment agents to secure a job - only to discover too late that they had been given empty promises and could not afford to return home.

"Some are in situations close to bonded labour," it said, adding that laws allowing employers to hold workers' passports prevented them from leaving abusive workplaces for fear of arrest.

"Coercive practices such as these are indicators of forced labour," it said.

Amnesty said its findings were based on interviews with more than 200 migrant workers, many of whom told horrifying stories of being abused, beaten, threatened with death, or at the least unpaid for long stretches.

A 26-year-old domestic helper from Indonesia said she was raped twice and attacked with a hot iron by her employer after being accused of not picking up the phone quickly enough.

"I didn't know why he told me to turn on the iron. He shouted, "Is that iron hot?" And then tried to iron me. Push the iron toward my body," the unidentified worker was quoted as saying.

Another worker, Mawar, who was only 15 when she came to Malaysia, said her recruitment agent burned her nipple with a cigarette, and forced her to clean the floor with her tongue "just like a dog".

"Another time the agent forced me to eat five cockroaches while they were still alive. She also forced me to drink urine from other workers," said Mawar, whose nationality was not given.

Amnesty also documented over a dozen cases in which Malaysian immigration officials allegedly handed over Myanmar detainees to traffickers operating on Malaysia's northern border with Thailand between 2006 and 2009.

"The Malaysian government has the responsibility to prevent such abuses, but instead facilitates trafficking through its loose regulation of recruitment agents and through laws and policies that fail to protect workers," it said.

An official from the home ministry, which oversees the immigration department, said it would not respond to the allegations until it had an opportunity to study the report.

Amnesty said that workers often face indiscriminate raids from authorities and demands for bribes from police, and that those who cannot pay end up in detention centres in deplorable conditions.

The government said last year it was mulling new laws to enshrine conditions for foreign workers, after persistent complaints that they lack protection.

"Until Malaysia's labour laws offer effective protection and are effectively enforced, exploitation will continue," said Michael Bochenek, Amnesty's policy director who authored the report.