The Australian government has restricted foreign diplomats bringing domestic workers into the country, a UN anti-slavery expert has reported, after two recent federal court cases exposed systemic exploitation a judge described as “slave-like working conditions”.

The United Nations special rapporteur on contemporary forms of slavery concluded a visit to Australia this week, with a particular focus on temporary migrant workers across the country.

Prof Tomoya Obokata said “a large number” of people had raised concerns with him that foreign domestic workers – brought into the country to work in the private homes of diplomats – faced widespread and largely invisible exploitation.

“The way the government is approaching it now, according to the information I have received, is that they are restricting the grant of those visas to a select few individuals, in order not to make it as widespread.”

Obokata said he was told the government was also “intensifying the information campaign” directed towards diplomatic missions, so that domestic workers were not exploited.

“I think it is the job of the federal government to make sure that the diplomatic community are fully aware of the working conditions and rights and entitlements and making sure that is enforced. I think-awareness raising is quite important.”

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Two recent federal court cases have brought the sustained, systemic domestic worker exploitation to public prominence.

In 2023, Indian national Seema Shergill was awarded $189,000 in unpaid wages and interest after working in Australia for a year earning less than $2,500 – about $9 a day.

The Indian high commissioner who employed her, Navdeep Suri Singh, was this year fined $97,200. But the Indian government, and Suri himself, have denied any wrongdoing. Suri told the Guardian Shergill was a diplomat and her case could only be resolved by Indian authorities.

Shergill has never been paid her unpaid wages.

In a further judgment in August this year, Sri Lankan mother of two Priyanka Danaratna was awarded more than half a million dollars – $543,300 – in unpaid wages and interest. Danaratna worked seven days a week, on average for 14 hours a day, for three years in Australia, during which she had only two days off, both of which were spent in hospital.

Danaratna had her passport seized, was not allowed outside and she told the court she was not given enough food. She was grossly exploited, paid just 65 cents an hour.

Her employer, Sri Lankan diplomat Himalee Arunatilaka, did not respond to repeated requests for comment, but her government said the domestic worker was paid a mutually agreed salary. Arunatilaka is now Sri Lanka’s permanent representative to the UN, based in Geneva.

Danaratna has not been given her unpaid wages.

In her judgment in the Shergill case, Justice Elizabeth Raper condemned the “slave-like working conditions” of some domestic workers, saying some spend their entire existence “entrapped within domestic servitude”.

“Their invisibility breeds exploitation.”

Government departments declined to comment on how diplomatic domestic worker visas – part of the subclass 403 category – were being restricted in the wake of these cases: whether diplomatic missions where exploitation had been uncovered were being blacklisted from visas, or whether a broader restraint on visas had been imposed.

Dfat told the Guardian it “makes clear to all foreign missions – through established policy and regular communications – the Australian government’s expectation that they adhere strictly to Australian laws and community expectations on pay, conditions, and standards of treatment.”

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A spokesperson for home affairs said domestic workers were only granted visas with written support from Dfat, and “evidence of employment contract that complies with the Fair Work Act”.

Department of home affairs officials speak with domestic workers as part of the visa application process, and flag concerns about possible exploitation with Dfat.

More broadly, the special rapporteur, in his interim report, said he was “seriously concerned by the treatment of temporary migrant workers in Australia”, including domestic workers in diplomatic homes, Pacific Australia Labour Mobility (Palm) scheme workers, working holiday visa holders, and people on student visas.

“I received credible information from a large number of stakeholders, including workers themselves, which clearly reveals disturbing, sometimes very serious, patterns of exploitative practices by employers, labour hire companies and migration agents,” Obokata said.

He cited evidence of deceptive recruitment, underpayment, racial discrimination, dangerous working conditions, harassment, threats of and actual violence, including sexual and gender-based violence.

Obokata said workers who left exploitative employers to take jobs in the informal economy faced further exploitation and abuse.

“These workers are also vulnerable to sexual and criminal exploitation by other actors. Many of these conditions may amount to contemporary forms of slavery.”

Obokata said the fundamental issue plaguing temporary work schemes in Australia was that they created a significant power imbalance between employers and workers, with workers generally tied to a single employer and dependent upon that employer for their right to work and even remain in the country.

“The power imbalance undoubtedly leads to under-reporting among workers, which in turn results in impunity among employers, labour hire companies or immigration agents.”

The NSW anti-slavery commissioner, James Cockayne, said the special rapporteur’s report was “a wake-up call to governments at all levels in Australia”.

“While the special rapporteur rightly applauds recent progress, his statement highlights significant modern slavery risks facing temporary migrant workers, international students, people with disabilities and sex workers.

“Prof Obokata joins a growing chorus of expert voices calling for Palm workers to be given greater labour market mobility and protections from exploitation.”

President of the Australian Council of Trade Unions, Michele O’Neil, said the special rapporteur’s report echoed the longstanding position of the union movement.

“All temporary migrant workers must have the ability to change their employer, this includes workers on the Palm programme, who are effectively bonded to their employer sponsor, meaning the employer essentially controls their paycheque and their passport – a huge modern slavery risk.”