CANBERRA, Australia -- An Australian man has been charged with sexually abusing twin girls he fathered several years ago to a Thai surrogate mother, media reported late Monday.

The man, who cannot be identified for legal reasons, was charged in a New South Wales state court last year with indecent dealings of a sexual nature with the children while they were around 4 and 5 years old, Australian Broadcasting Corp. and Nine Network television reported.

The charges are the latest blow to the credibility to the commercial surrogacy industry in Thailand, which the Southeast Asian country's military junta has vowed to shut down.

Court documents reveal that the father, aged in his 50s, has also been charged with possessing child pornography materials which were found after a raid on his home, ABC and Nine reported.

The man, who denies the allegations, will go to trial in December. He is currently free on bail.

The twins were born around seven years ago to a 23-year-old Thai surrogate mother, Siriwan Nitichad, also known as Aon, who lives in the Petchabun province, 400 kilometres (250 miles) north of Bangkok.

Encouraged by a relative and with her husband's agreement, Aon agreed to act as a surrogate for a couple from Australia who could not conceive on their own, ABC reported. The man was then aged in his 40s and his wife was older, Nine reported.

"They said they were just married and they really wanted to have a baby so much," Aon told ABC.

"She said her husband wanted to have a baby so much, please help them, please help them," Aon added.

Aon agreed to use her own eggs with the Australian man's sperm. Aon said she was paid a total of 170,000 Thai baht ($5,300) for her services.

She said the twins were born with lung and other health problems. They were four or five months old before she handed them over to the Australians.

"They were so lovely, I wanted them to stay with me, I did not want to let them go," Aon told ABC.

"If they asked if they could cancel their payment and we kept the babies, I would definitely have said 'yes,"' she added.

Court documents reveal the father became unemployed, allegedly had a violent temper, and the marriage broke down, ABC reported.

Aon was told of the allegations in June 2013, ABC reported.

"I felt terrible. I felt very bad. I don't know how to describe it," Aon said.

The children are now in the care of the ex-wife of the accused man, and Australian child welfare authorities are working on plans for their care, ABC reported.

Ilya Smirnoff, executive director of Childline Thailand Foundation, a child welfare organization which runs safe houses for children, has been asked by Australian authorities to help with the case.

"We have been contacted by the international social service representative from Australia to make an assessment for the possible placement of the children back to Thailand," Smirnoff told ABC.

That would reunite the children with their surrogate and biological mother, but there are complications.

"They don't even speak any word of Thai, they don't know that they are half Thai or have any connection to Thailand," Smirnoff said.

Smirnoff was not immediately available for comment Tuesday. Australia's Department of Foreign Affairs and Trade, which is negotiating with Thai authorities to help Australian couples bring home babies already conceived by Thai surrogates before the recent crackdown on the industry, would not immediately comment Tuesday.

Thai authorities have been cracking down on the largely unregulated surrogacy industry since recent publicity over allegations that an Australian couple had abandoned a baby boy born to a surrogate Thai mother after learning he had Down syndrome. The couple, who took the boy's healthy twin sister home, has said they wanted to bring the boy with them and the Thai surrogate has acknowledged she kept him because she feared he would end up in a state institution.

Thailand and Australia are working out a transition process for an expected 150 Australian couples and Thai surrogate mothers expected to give birth over the next several months.