Surrogacy Australia says it is shocked and outraged that an Australian couple abandoned a baby in Thailand with his surrogate mother after he was found to have Down syndrome and a life-threatening heart condition.

Pattaramon Chanbua has told the Australian Broadcasting Corporation (ABC) she gave birth to twins after agreeing to be a surrogate with a promised payment of about $16,000.

The Western Australian couple rejected six-month-old Gammy and only took his healthy sister home with them, and Pattaramon says she cannot afford Gammy's medical treatment. She told the ABC she refused the couple's request to terminate the pregnancy because in Thai culture that would be considered sinful.

W hy does he have to be abandoned while the other baby has it easy? I feel sorry for him. I don't know what to do. I chose to have him, not to hurt him. I love him. - Surrogate mother Pattaramon Chanbua

Australia's Department of Foreign Affairs says it is concerned by the reports and is consulting with Thai authorities. In Australia, people from New South Wales, Queensland and the ACT (Australian Capital Territory) are prohibited from entering a commercial surrogacy agreement overseas.

Rachel Kunde, executive director of Surrogacy Australia, said the case is shocking. "Someone's left a baby behind and separated it from its twin and pretty much just disregarded that it was their child, which is something that is just unfathomable for people to think about," she said.

She is worried about a knee-jerk reaction to the case could lead to an outright ban on surrogacy arrangements.

"We're hoping that this is actually a positive step towards better regulation," Ms Kunde said. "Of course we don't think it should be banned but we do think there should be more regulation and that surrogacy should be more accessible in Australia, because this is why people are going overseas because surrogacy isn't as easily done here."

Prime Minister Tony Abbott said it's "an incredibly sad story."

Pattaramon Chanbua, who has two other children of her own, says she cannot afford Gammy's medical treatment. (Australian Broadcasting Corporation)

"I guess it illustrates some of the pitfalls involved in this particular business. It's a very, very sad story and I hate to think that a child could be abandoned like that," he said.

He said there may be some support for the surrogate family. "Let's look at things and see what might be possible," he said. 'Why does he have to be abandoned?'

Along with Down syndrome, baby Gammy has a hole in his heart. He is now in hospital undergoing treatment.

Pattaramon, 21, lives about 90 kilometres south of Bangkok with her two other children — a six-year-old and a three-year-old. Pattaramon says she cannot afford the expensive treatment the baby needs.

"I felt sorry for the boy. It was like this is the adults' fault and who is he to have to endure something like this even though it's not his fault?" Pattaramon said. "Why does he have to be abandoned while the other baby has it easy?

"I feel sorry for him. I don't know what to do. I chose to have him, not to hurt him. I love him. He was in my tummy for nine months, it's like my child. I treat him like my other children, never think you are not my child and I don't care for you, never."

While Gammy's Australian parents abandoned him, the general public has not. A campaign on fundraising web site GoFundMe has raised more than $100,000.

In Thailand, the ruling military is cracking down on an often unregulated IVF and surrogacy industry — and for Australians already using Thai surrogates it is an anxious time.