Pattaramon Chanbua answers question during a press conference at the Samitivej hospital in Chonburi province on Tuesday.

AFP

An Australian couple accused of abandoning their Down's syndrome baby born to a Thai surrogate mother on Tuesday said she has misled the world over what happened, according to a friend of the family.

The couple, who cannot be named, have come under heavy criticism for apparently rejecting the boy, Gammy, at birth and taking only his healthy twin sister back to their home in Bunbury, south of Perth, from Thailand.

The surrogate mother, Pattaramon Chanbua, has insisted she will raise the seven-month-old child after saying the biological parents at first requested an abortion and then walked away when they learned of his condition.

But the Australian couple said in a statement, issued through the friend to their local newspaper the Bunbury Mail, the allegations were false and they did not know he had Down's syndrome, although they were aware he had a congenital heart condition.

"Gammy was very sick when he was born and the biological parents were told he would not survive and he had a day, at best, to live and to say goodbye," the friend, a woman, told the newspaper, without saying who told them this.

The birth of the twins was supposed to take place at a major international hospital in Thailand but Pattharamon went to another facility, which made the surrogacy agreement void, according to the newspaper.

This meant that the couple had no legal rights to the babies although the surrogate mother finally agreed to hand over the girl, the report said.

"The biological parents were heartbroken that they couldn't take their boy with them and never wanted to give him up, but to stay would risk them losing their daughter also," the friend said.

She added that allegations that the couple "ignored" Gammy when they visited the hospital were untrue and they had bought gifts for both infants.

"They prayed for Gammy to survive but were told by doctors that he was too sick, not because of the Down's syndrome but because of his heart and lung conditions and infection."

The friend added that the couple spent two months in Thailand but due to military unrest at the time felt they had no option but to leave without Gammy.

"This has been absolutely devastating for them, they are on the edge," she said.

The case has sparked fevered debate on the moral and legal grounding of international surrogacy.

While the full picture of exactly what happened remains unclear, Pattaramon insisted to AFP on Tuesday she had been transparent.

"I have never lied or hidden anything. The truth is the truth, it's up to society to make their own judgement," she said.

Pattaramon has said she agreed to carry another Thai donor's egg fertilised by the Australian man, reportedly aged 56, in exchange for around US$14,900.