Shahid Mahmood told the ABC's Four Corners program that he slept in a storage space in the basement of the home of Pakistani High Commissioner Naela Chohan for 18 months before seeking help with Canberra Legal Aid. He described his pay of around $100 a week being sent to his family in Pakistan every few months.

Ruth (whose last name wasn't used in the report), said she was was placed in the home of a Saudi Arabian diplomat after answering an advertisement from a recruitment company in the Philippines. Although she signed a contract saying she would be paid $2150 a month, she was paid only about $250 a month, which was given to her husband. When she first arrived in Canberra, the room she was to sleep in didn't even have a bed, her passport was taken away from her.

Eden, also from the Philippines, said she worked up to 18 hours a day, seven days a week for just $350 a week for a former ambassador for the Philippines in Australia. She left the embassy with her now-husband Gary, but is unable to return to her children in Manila.

Mr Mahmood was granted permanent residency by the Australian government in September last year, the ABC reported that a letter from the department of immigration said "The Attorney-General has issued a certificate confirming that you have made a contribution to, and cooperated closely with, an investigation".

Ms Chohan, who is still High Commissioner for Pakistan, gave a statement to the ABC saying "I can assure you that all and each of the allegations … are baseless, unfounded and motivated".

ABC's Four Corners program revealed on Monday that the Salvation Army has dealt with more than 20 cases of workers being exploited in diplomatic households, mostly in Canberra.

Unions ACT secretary Alex White said embassy workers had previously contacted the peak body about their treatment, however they chose not to take the matters further out of fear.

"It's a significant number and it's happening in some of the richer suburbs in Canberra, because that's where all the embassies are," Mr White said.

"The embassy staff and diplomats shouldn't be allowed to get away with this, and they are allowed to by the federal government."

The union peak body has previously proposed that the ACT government becomes a sponsor of last resort for workers on visas being threatened with deportation if they leave abusive employers, however Mr White said the idea had been bogged down in legal review.

"There's a lot of denial in the community that this kind of exploitation happens in Canberra, but it is, and it's very serious," Mr White said.

Secretary of the ACT branch of United Voice Lyndal Ryan said she was concerned about any situation that tied a person's visa to their employment, and that members of her union had reported issues with exploitation in the embassies to the union.

"In any circumstances where your job is tied to a visa, you're a very vulnerable worker. It's especially scary for you if they can sack you and send you home," she said.

"Not only do they fear for themselves but for their families in their home country."

Ms Ryan echoed Mr White's call for the ACT government to provide an avenue of protection for workers seeking to escape exploitative environments, describing it as a "very neat solution".

"People would be much more inclined to come forward if they could be assured they wouldn't face retribution," Ms Ryan said.

If the ACT government were to take action on the issue it would send a signal to those who seek to exploit workers, Ms Ryan said.

"For the people who are exploiting workers, they are doing so not necessarily out of ignorance but out of an assessment of the risk for them, and the risks for them are too small," she said.

ACT Police told Fairfax Media that it had received complaints from workers within diplomatic residencies or embassies. "Allegations such as these are inherently complex and require consultation with a number of government agencies and non-government organisations," a spokesperson said.

Foreign Affairs Minister Julie Bishop said "the Australian Government has strict procedures and checks to ensure foreign diplomats comply with Australian laws and regulations when they bring privately employed staff to work in their households".

"DFAT treats allegations of mistreatment of domestic workers by foreign diplomats very seriously and are a matter for the police," she said.

Timor-Leste ambassador Abel Guterres is the dean of the diplomatic corps in Australia, but refused to comment on the issue to Fairfax Media.