BANGKOK: Twelve months ago Baby Gammy was chronically unwell with a heart condition and abandoned in Thailand by his Australian biological parents.

But Hands Across the Water, the Australian charity that is caring for the Down Syndrome toddler, says his "transformation has been nothing short of remarkable."

Releasing photographs of a happy-looking boy, the charity said that at one stage he was "incredibly sick" with his life in the balance.

"Now look at him. A true reflection of love and happiness," the charity said on its Facebook page.

When Fairfax Media revealed Gammy's plight last year donors gave more than $235,000 which Hands Across the Water is using to assist the baby and his family who live in a village near Bangkok.

Gammy's mother Pattaramon Chanbua has obtained Australian citizenship for the baby, allowing him to receive medical and other benefits in Australia if necessary.

The abandonment of Gammy by his biological parents David and Wendy Farnell prompted Thailand's military rulers to shut down the country's then booming surrogacy industry.

Earlier this year Hands Across the Water rebuffed attempts by Mr and Mrs Farnell to gain access to donations raised for Gammy.

The Farnells are caring for Gammy's twin sister Pipah at their home in Western Australia.

The move infuriated Ms Chanbua.

"He does not deserve or have any rights to the fund as he abandoned Gammy in the first place," she said, referring to Mr Farnell, a convicted child sex offender.

Ms Chanbua depends on monthly payments from Hands Across the Water for Gammy's medical and other costs.

The charity has used some of the money to buy the family a home.