Police are pressing charges against a Bangkok doctor suspected of involvement in a transnational surrogacy ring.
Police did not disclose the suspect's identity on Tuesday but noted that he faces charges of "conspiring in a transnational criminal activity and engaging in commercial surrogacy".
Surrogacy is illegal under Thai law.
The doctor worked at a state-run hospital in Bangkok, according to police.
The Royal Thai Police's Anti-Trafficking in Persons Division (ATPD) said the suspect arrived at its headquarters, after he was summoned, to acknowledge the charges on Tuesday.
Police said the suspect was part of a "gang" and he was responsible for inseminating and transferring embryos into surrogate mothers' wombs.
Police said the suspect was released on bail, adding four other doctors will be summoned to provide testimony on the matter.
Police on Tuesday arrested a woman for allegedly being connected to a group that ran a surrogacy operation out of a house in Samut Prakan province's Phra Pradaeng district.
Police said the group was connected to the doctor in Bangkok.
The woman was allegedly in charge of transferring her group's money.
Like the doctor, the suspect is accused of colluding in a transnational criminal activity and engaging in commercial surrogacy and was released on bail.
ATPD chief Pol Maj Gen Worawat Watnakornbancha on Tuesday said police are preparing to arrest 10 more people believed to have been involved in the case, including other doctors.
Investigators are expected to wrap up their probe next week, Maj Gen Worawat said, noting case files have been forwarded to prosecutors.
On Feb 13, nine suspects, comprising seven Thais and two Chinese nationals, were arrested in raids in Bangkok, Pathum Thani and Sukhothai. They also face charges of colluding in a transnational criminal activity and engaging in commercial surrogacy.
The raids were conducted after police identified a group of Chinese nationals who were allegedly hiring Thai women to serve as surrogate mothers.
The following day, police from the ATPD arrested two more Thai suspects in Chiang Mai.
Police said they were hired by the Chinese group to work as brokers between them and potential surrogate mothers. This pair also face the same charges.
Police believe illegal surrogacy activities began in the kingdom back in 2012. They said at least 100 women had been recruited as surrogate mothers.
Police said that in the case of the Chinese group, the women received up to 450,000 baht per pregnancy.
The surrogates travelled to neighbouring countries to be inseminated and returned to the kingdom to deliver the babies, police said, noting some surrogates were sent to China to give birth there.
Investigators questioned several women in Pathum Thani who were allegedly hired as surrogates and found that 15 babies resulting from assisted reproduction procedures were included on household registration forms.