The case is the second in as many months to ignite debate about commercial surrogacy, after another Australian couple left a surrogate baby which was born with Down's syndrome in Thailand.
The Australian Broadcasting Corporation said that in the latest case the Thai mother, Siriwan Nitichad, had agreed to carry a child for a man and his wife who had not been able to conceive.
"She said her husband wanted to have a baby so much, please help them, please help them," the woman, who is also known as Aon, told the broadcaster.
Ilya Smirnoff, executive director of Childline Thailand, an organisation which has been involved in the case, did not name the mother but said he thought the children were now aged about seven and that the allegations dated back some two years.
"Initially she (the mother) felt pleased to be a surrogate and do a good thing by helping the couple...But when she found out about this (abuse charge) she was extremely devastated," he told AFP.
A Sydney-based NGO called International Social Service Australia confirmed that an Australian state government had contacted it about two years ago, seeking to trace a surrogate mother in Thailand, and it had contacted Childline.
It said it helped to obtain an "assessment on her (the mother's) suitability to provide long-term care for the children", but that ultimately the children had not been taken back to Thailand.
It is understood that after the twins were born, the couple took them back to Australia but that the marriage later broke up.
