Police allege the man would record and distribute footage and images of the horrific crimes.
The man was first arrested in May last year when authorities searched the modelling agency's headquarters while investigating the alleged activities of another man identified as part of a SA JACET investigation.
Police in Thailand seized several electronic devices allegedly containing more than half a million files of child abuse material and charged the 28-year-old with possessing the illegal content.
Then, on February 11 of this year, specialist police from Thailand again searched the man's home, which he had been using as his modelling agency, and charged him with the further offences.
The international investigation — which started in Asia — has already led to the jailing of nine offenders in Thailand and Australia since May 2018.
The investigation also helped police identify more than 100 child victims, leading to officers in Australia and overseas removing a number of children from immediate harm.
The investigation was extensive, with officers from JACET reviewing more than 850,000 video and image files seized from the Adelaide-based administrator.
The footage showed a Thai national, found to be living in Adelaide and believed to be the one running the website, allegedly abusing multiple children, including babies.
In May 2019, he was sentenced to 40 years and three months' in jail in Adelaide for his crimes – the longest sentence imposed for child sexual offences in Australia at the time.
Australian Federal Police Commander Asia Peter Sykora congratulated Thai police and said it was an example of international collaboration.
"This significant result is a testament to their dedication, and shows the impact of law enforcement agencies working together, sharing expertise and intelligence," Commander Sykora said.
"The AFP and our partners in Australia and overseas have the same determination to protect and remove children from abuse and bring their perpetrators to justice.
"There are no borders when it comes to protecting children and investigations are ongoing to identify and rescue victims wherever they are located."
SA JACET, which consists of Australian Federal Police and South Australia Police officers, launched Operation Bayldon in late 2017 after a referral from Interpol.
The Interpol Crimes Against Children, Asia, with assistance from the Thai Department of Special Investigation, identified a website trading in pay-per-view child abuse material, featuring boys from Asia.
An administrator of the abhorrent website, a Thai national, was found to live in Adelaide. In January 2018, simultaneous searches were conducted in Thailand by the Department of Special Investigation, and in Adelaide by the SA JACET, resulting in the arrest of offenders in Australia and Thailand.
The United States' Homeland Security Investigations and New Zealand Police also provided vital assistance during the long-running investigation.
