Ms Davis-Charles was sent back to one of the country's harshest overcrowded prisons.

Police alleged the 49-year-old mother of six from Melbourne, falsified documents, including birth certificates, to smooth passage of surrogacy paperwork through Cambodia's murky legal system and the Australian embassy in Cambodia.

Her lawyer, Cheang Sophoan, told Fairfax Media the decision was a violation of her rights because she has already spent six months in jail. He said the main charge she faces relating to arranging surrogacies only carries a six-month sentence.

Prosecutors requested the delay because four surrogate mothers had failed to turn up in court. Mr Sophoan said the court already had received the witnesses' testimony through court documents.

Ms Davis-Charles refused to speak to Fairfax Media after the hearing but appeared distressed. She arrived in court in handcuffs and wearing orange prison uniform with "Tammy" sewn on the back.

For more than a year Ms Davis-Charles ignored warnings from the Australian government that commercial surrogacy was illegal in Cambodia. In that time, Fertility Solutions PGD, the company she founded, signed at least 25 surrogacy agreements, most of them with Australian biological parents.

Police arrested her with two Cambodians in October last year as they cracked down on more than 50 surrogacy clinics and brokers in Phnom Penh.

Ms Davis-Charles was sent to the notorious Prey Sar prison on the outskirts of Phnom Penh, where conditions are harsh, as the human drama unfolded.

Surrogate mothers fled their villages, fearing arrest and leaving them without access to medicines and medical check-ups. Authorities refused to issue exit visas for all surrogacy cases where the newborn had a foreign passport, leaving dozens of babies and families in legal limbo.

Authorities demanded the Australian biological parents identify themselves to the government but few, if any, did. Surrogacy groups described their situation as "desperate".

But in April, Mr Hun Sen approved a strategy to allow babies to leave Cambodia if biological parents could prove a DNA link to their babies and proved in court they would be competent parents.

Surrogate mothers also have to testify they are willing to give up their babies. Under Cambodian law the birth mother has custody of a child.

Similar strategies were implemented in Thailand after that country's military government cracked down on a booming surrogacy industry in Bangkok following the Baby Gammy scandal in 2014.

Cambodia then emerged as the new centre for commercial surrogacy in Asia after surrogacy operators had also been chased out of India and Nepal.

Now clinics have opened in the Lao capital Vientiane where there are scant neo-natal facilities.

For months Ms Davis-Charles declined to comment publicly as her lawyer pressed for a speedy hearing of her case. Two of her children were born through surrogacy.

Police said Ms Davis-Charles' company was paid $US50,000 ($67,000) per baby, recruiting surrogates from impoverished villages where they were promised fees totally about $US10,000.

Hour Vanny, a 35-year-old surrogate, told Fairfax Media last year that her agreement with Ms Davis-Charles' company stipulated she have a caesarean, although she had already given birth to two children naturally without any complications.

"I was terrified and had been panicking," she said of the day of the birth in a Phnom Penh hospital.

"I pleaded to be allowed to have the birth naturally but they said it was a requirement???when I heard the cry I looked down to see the baby, but they immediately took her away from me. I didn't even get to see her face."

The biological father Charles Artman, 27, from Caulfield in Melbourne, was able to take the baby home before authorities imposed the exit-visa ban.

Fairfax Media obtained a copy of a birth certificate issued by a clinic in Phnom Penh which claimed that Ghana-born Mr Artman was Ms Hour Vanny's husband.

But Ms Hour Vanny said she had never married Mr Artman and had only met him briefly after the birth of the baby, at a clinic.

Mr Artman has declined to comment.

Ms Hour Vanny said she and her husband Vann Kun, 36, agreed she would carry Mr Artman's baby because they owed thousands of dollars to loan sharks and their only income was from Vann Kun's motorcycle taxi work.

They saw the $US10,000 offered by Ms Davis-Charles as a small fortune.

"I had to pay the funeral of my mother and I had responsibility to take care of my family," Ms Hour Vanny said sitting with her two-year-old son asleep on her lap outside a two-room shack in a squatter area near Phnom Penh.