A Melbourne couple has been accused of keeping an illegal immigrant as a slave for eight years and for allegedly threatening to return her to her Indian family "in a coffin".

Kandasamy and Kumuthini Kannan forced the woman, who cannot be named for legal reasons, live with them as a domestic help. They have been charged for keeping her as a slave at their Mount Waverley home.

According to Melbourne Magistrates Court's documents on Wednesday (13 December), the woman's son-in-law had contacted the couple after he and his wife came to know that she was seriously ill, Daily Mail reported.

The man claimed that he was verbally abused with "obscene and vulgar words" by Kandasamy, who also demanded money for the woman to return back to her home village in Tamil Nadu, in south India.

The woman's son-in-law said that Kumuthini had threatened him if they did not pay. She also asked if "they wanted their mother returned in a coffin".

The phone call was made after a series of alleged emails between the couple and the woman's son-in-law, who had asked the couple to send back the woman in May 2015, Daily Mail reported.

The court heard that Kumuthini had replied by email saying: "Ask her to go f*** herself!!!" and "F*** you!"

The victim, who is in her 50s, said that she had come to Australia in 2007 after she was allegedly promised a better life and $143 a month (£107.09; Indian rupees 8000) to work as a domestic help for the pair.

She, however, said that she wasn't paid any money and was instead beaten and neglected.

The woman was finally taken to Box Hill Hospital by ambulance in July 2015 as she was suffering from urinary sepsis, untreated diabetes, hypothermia, skin lesions. All her teeth had also fallen out.

Earlier this week, the woman gave evidence about her eight years of working for the Kannans and said that she was beaten more than 10 times.

She said that Kumuthini would hit her with a frozen chicken. She had even poured boiling water on her legs, threw hot tea on her face, and had also cut her wrist with a knife, Daily Mail reported.

The woman's son-in-law who spoke via an interpreter from India said that he met the couple while they were on a holiday in Tamil Nadu. He said he had sent the woman "wholeheartedly" to work for the couple in Australia. When asked if there was any financial difficulty at the time, he denied but agreed that the Kannans had sent small amounts of money.

The couple are now facing a five-day committal hearing which will decide if the case will go to trial, according to Daily Mail.