CANBERRA, Australia (AP) -- A newborn Down syndrome baby left by his Australian biological father with his poor surrogate mother in Thailand was one of several cases of surrogate children abandoned because of defects, an expert told a parliamentary inquiry on Thursday.

The high-profile case of baby Gammy prompted the Thai government to ban surrogacy in 2014, and an Australian parliamentary committee launched a review of Australia's laws that prohibit commercial surrogacy.

Gammy was left with his surrogate mother, Pattaramon Chanbua, a 21-year-old food vendor with two young children of her own, when he was born in December 2013. Pattaramon accused the boy's biological parents, Wendy and David Farnell, of leaving her with the infant while taking his healthy twin sister, Pipah, back with them to Australia.

The Farnells denied they had abandoned their son because of his disability, and accused Pattaramon of demanding to keep the boy.

Chief Judge John Pascoe, head of the Federal Circuit Court of Australia and an expert on surrogacy, told the House of Representatives Standing Committee on Social Policy and Legal Affairs that Gammy was not a unique case.

"We believe that baby Gammy was certainly not an isolated incidence," Pascoe said.

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Pascoe later told The Associated Press that there was anecdotal evidence that commissioning parents would often not accept babies born with "defects and problems."

Gammy continues to be raised by his surrogate mother in the town of Sri Racha on the east coast of Thailand with the help of a 250,000 Australian dollar ($180,000) fund raised for him by the Australian charity Hands Across the Water.

"He's a happy, healthy and very much loved 2-year-old boy," charity founder Peter Baines said.

Gammy was now a dual national, having taken out Australian citizenship last year based on his biological father's nationality, Baines said.

Pascoe told the inquiry that a baby left by Australian parents in India in 2012 in another high-profile surrogacy case could also have become an Australian citizen, but authorities had been unable to find him.

The parents returned to Sydney with a baby daughter born to an Indian surrogate, but left behind her healthy twin brother because the family already had a son. The Australian Embassy in New Delhi had warned the parents that they risked leaving him stateless because India did not recognize surrogate children as citizens.

Pascoe said since India and Thailand closed down their surrogacy industries, prospective parents turned to Nepal, and following a Nepalese crackdown, Cambodia.

Pascoe recommended that Australian parents lose their right to automatic citizenship for surrogate babies to encourage them to choose better-regulated countries.

Pascoe will represent Australia at The Hague in negotiations for a possible international convention on surrogacy.