She had protested about the surgery, having delivered three previous babies naturally without a problem.

But Australian nurse and surrogacy agent Tammy Davis-Charles insisted, as she had with other surrogates recruited from poor Cambodian villages.

"I was terrified and had been panicking. I pleaded to be allowed to have the birth naturally but they said it was a requirement," says the 35-year-old Cambodian surrogate mother. "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 baby was taken to a ward in a Phnom Penh clinic where a 27-year-old Ghana-born man, Charles Artman, was waiting.

Little is known about Artman, except that he paid $US50,000 ($67,000) to take the baby out of Cambodia on an Australian passport issued by the Australian embassy. According to Cambodian police, fake documents were presented at the embassy showing that Artman and Hour Vanny were married when in fact she had been married to a Cambodian man for years. Fairfax Media has not been able to contact Mr Artman to seek comment from him.

Cambodian police allege that Davis-Charles, a mother of six from Melbourne, falsified documents, including birth certificates, to smooth the passage of paperwork through the country's murky legal system and the Australian embassy to get approval for surrogate-born babies to leave the country.

For more than a year 49-year-old Davis-Charles ignored warnings from the Australian government that commercial surrogacy was illegal in Cambodia as Fertility Solutions PGD, the company she founded, signed at least 25 surrogacy agreements, most of them with Australian biological parents. In October, Cambodia issued a proclamation banning the practice.

Now she languishes in Phnom Penh's harsh Prey Sar prison awaiting trial. She could be jailed for two years. A crisis is unfolding in Cambodian villages, with dozens of pregnant surrogates going into hiding. They fear arrest under a crackdown on 50 surrogacy businesses that opened in Cambodia after crackdowns in Thailand, India and Sri Lanka.

Officials in Phnom Penh have declared that commercial surrogacy constitutes human trafficking and are blocking biological parents taking babies from the deeply Buddhist nation, including some granted Australian passports.

As Hour Vanny lay in her ward bed after the caesarean in late August, she anxiously waited to see the baby who she knew was in a nearby ward.

"On the second day a nurse came by and said the father has taken the baby away," she says. "I was upset ... I loved the baby and wanted to see her – just her face, anything – but what could I do? I had volunteered and agreed to let the man take the baby for money."

It was easy for Davis-Charles' recruiters to find surrogates in Khmounh squatter settlement, 20 kilometres from Phnom Penh along a muddy, rubbish-strewn track, where several hundred families live in huts pieced together from scrap iron and wood.

Like most of the villagers, Hour Vanny and her husband Vann Kun, 36, owe several thousand dollars to loan sharks, with their only income coming from Vann Kun's motorcycle taxi work.

They saw the $US10,000 Davis-Charles promised for Hour Vanny to carry a baby as a small fortune.

"I had to pay for the funeral of my mother and I had responsibility to take care of my family," Hour Vanny says, sitting outside her family's two-room shack with her two-year-old son Kun Raksa sleeping on her lap. "We desperately needed the money and so I spoke about it with my husband and he agreed for me to be a surrogate."

Hour Vanny did not hear anything about the baby or Artman for more than a month after she left the clinic.

"I kept waiting and waiting. I couldn't sleep at night. My husband feared we would not get paid and the loan sharks wanted their money," she says.

Eventually she got a telephone call telling her to go to the Australian embassy, where Artman was waiting. As she cannot read or write she said she had little idea what was going on, except when an interpreter asked her: "Do you accept for the baby to be taken to Australia by this man?"

"I said 'Yes, I agree', because I had volunteered. What else could I do?" she says.

Days later Hour Vanny said she briefly saw Artman and the baby at a clinic when blood samples were taken and on one other occasion at a Cambodian immigration office near Phnom Penh airport, where Artman was seeking final approval to take the baby out of the country.

"The baby's skin was a little bit dark like the man, with curly hair. We were supposed to act like husband and wife and he let me hold the baby for about half an hour in front of others," she says. "At one point a man in the [Cambodian immigration] office asked Artman who was his wife and he pointed at me."

The Australian government has refused to comment on the case or on the validity of the documents presented. A statement by the Department of Foreign Affairs and Trade to Fairfax Media said: "The regulation of surrogacy in foreign jurisdictions is a matter for those jurisdictions. The Australian Embassy is monitoring the development of surrogacy arrangements in Cambodia. Any updated advice will be placed on the Department of Foreign Affairs and Trade's International Surrogacy bulletin and Smartraveller website".

Surrogacy is little understood in Cambodian society, which has endured the Khmer Rouge genocide of the 1970s, years of civil war and three decades of corrupt rule by the regime of Hun Sen.

Cambodian officials struggled for months to decide how to legally treat surrogacy after Davis-Charles and other surrogacy operators moved to Phnom Penh from Thailand, where the military government had shut down the industry in the wake of the Baby Gammy scandal in 2014.

Oeun Sam Art, a Buddhist monk and vice-dean of Phnom Penh's Preah Sihanouk Raja Buddhist University, says under Buddhism surrogacy is immoral for the surrogate as well as the biological parents, violating four virtues of the religion.

He says while payments to the surrogates are huge in the context of Cambodian society, the "lack of morality and misconduct when babies are not born naturally and according to the [Buddhist] virtues cause great danger to society".

Hour Vanny said she feels sorry for Davis-Charles, who sent the final payments to her this month. "I would be prepared to testify for her in court," she says, adding that other surrogates who have been paid feel the same way.

But Cambodian authorities have frozen Davis-Charles' bank accounts in Phnom Penh and more than 20 surrogates who have either given birth to babies or are carrying them fear they will not be paid.

Som Tha Satry, a 33-year-old divorced mother with a nine-year-old son gave birth to twins, a boy and girl, on October 26, by caesarean surgery. The twins were immediately given to an American man in his early 30s who took them to a rented condominium in the capital.

"I am very worried. I don't know if the babies are still in Cambodia or not. I love the babies. They were inside my body. But now Tammy is in jail I don't know what to do," Som Tha Satry says. "For me the most important thing is the money. I am owed $US6200."

Asked what she would do if she does not get paid and the babies are still in Cambodia, she replies: "I would want to take the babies back."

Under Cambodian law the birth mother is considered the lawful mother.

Like other surrogates interviewed by Fairfax Media, Som Tha Satry doesn't have copies of the paperwork prepared by Fertility Solutions, only a photograph of the twins taken shortly after their birth. Like the others, she has not been told the source of the embryo that was implanted in her and knows virtually nothing about the biological parent or parents.

Surrogates said they were told that if the baby they are carrying has physical deformities they would have to keep the child (although this is not stated in their two-page letter of contract).

Since Davis-Charles' arrest last week, at least 10 of the surrogates she dealt with have left Khmounh settlement, and dozens of others across the country have gone into hiding, prompting concerns about their health and that of the babies.

"I am scared. I need help and support," says 33-year-old Touch Sokhy, who had an embryo organised by an Australian man implanted in June, and is expecting to give birth in March.

Touch Sokhy, who has two sons aged five and three, says she doesn't have money for her monthly medical check-up or medicines. "I don't hold out hope I will get paid because my boss Tammy is now in prison," she says, adding she was promised  $US400 a month to carry the baby and then a final payment to bring the total amount to $US10,000.

"I hope my lawyer can solve the problem but he said he would only contact me after delivery of the baby. I am very worried."

Mith Sithoeun, 37, who had an embryo implanted in July, has fled the Khmounh settlement for her home province of Prey Veng and said she has no idea what to do when the baby is born next year. She has already missed one scheduled doctor's check-up and doesn't have the money to pay for more.

She has not met the baby's intending parents and doesn't know anything about them. She has only met Davis-Charles, whose trial is not expected to take place for months.

"I was promised  $US10,000 and am worried I will not get the money," she says.

In April, Mith Sithoeun's younger sister Mith Sithon, 33, gave birth to a surrogacy baby for an Australian man called John whom she believed had a same-sex partner. "John was very kind. We took a stroll in the park like husband and wife. He gave me extra money. Tammy was also good to me. I got paid," she says.

Meanwhile, Hour Vanny is paying off her debts and arranging for her children aged nine, six and two to go to school. She says that if surrogacy is legalised she would agree to carry another baby for $US10,000, but believes she will now be considered too old.

She often thinks about the baby and the mysterious Australian man who took her away, and who only ever uttered a few words to her that she had not understood.

"It is very hard to describe what is in my mind about all this. I already consider the man [Artman] to be the father," she says. "But it if turns out he is not a good man and has not looked after my baby, my thinking is that there will be bad karma for him."