Hands Across the Water collected more than 6000 donations for Gammy, who lives with his Thai surrogate mother Pattaramon Chanbua in Thailand.

But now Gammy's biological father, convicted sex offender David Farnell and his wife Wendy Li, who left Gammy in Thailand because he has Down syndrome, want access to the money, the Charity has confirmed.

Charity founder Peter Baines said he had been aware of the proposal for several weeks but did not understand why the claim would be made.

He said he was deeply concerned at the application to get access to the money, which totals $235,062.

"I believe the intent of those who donated the funds was very clear, they expected those funds to be used for the support of Gammy and his long term future, nothing else," he said.

"As Chairman and Founder of Hands Across the Water I take this matter very seriously and we are doing all we can to ensure that the money that was donated remains for the care of Gammy, which we believe was the intent of those who so generously donated the funds."

Fairfax Media understands the Farnells may be seeking to access the money to assist in funding their legal costs.

Earlier today, Pattaramon Chanbua told the ABC that she thought Mr Farnell gone crazy.

"He does not deserve or have any rights to the fund as he abandoned Gammy in the first place," she said.

Mr Baines said the money was purely for Gammy.

"The original appeal that was commenced was made by a group of concerned Australians who learnt that Gammy was born with Down syndrome and was left behind in Thailand," he said.

"Those who set up the fund to raise money were overwhelmed with the response once the story became public and reached out to Hands Across the Water asking for assistance, and indeed for us to manage the matter moving forward.

"Since Hands took responsibility for Gammy and the donated funds we have made a commitment to care for him for the long-term duration."

Efforts to contact Mr Farnell have been unsuccessful.