Nearly 1,500 children are suspected of receiving fake birth registrations through a network linked to eight private hospitals to obtain fraudulent Thai citizenship, said deputy national police chief Pol Gen Samran Nualma.

He said on Saturday four more accomplices have been arrested, including two Thais, Mong and Wor, who acted as Thai fathers in the scheme, and two Chinese nationals: Si, the mother, and Mr Hu, the biological father.

Prior to the arrests, police interviewed witnesses, checked medical records and birth notification documents, and examined the DNA of the fathers, mothers and children.

They found a Chinese woman and her husband wanted both their children to have Thai nationality. Mong and Wor were hired despite having no prior relationship with them. Both Thai men agreed to use personal documents to declare fatherhood in exchange for payment.

Pol Gen Samran said they were charged with jointly making false statements to officials, using forged official documents, and fraudulently registering citizens to illegally obtain Thai citizenship.

The registrar has revoked the registration entries and Thai citizenship of all children acquired fraudulently. The Immigration Bureau is being contacted to consider legal action against any foreign nationals involved, he said.

The operation to dismantle the network, conducted from July 9–24, resulted in the identification of 22 suspected children and the arrest of 37 perpetrators: 16 Thai fake fathers, 13 Chinese mothers, six Chinese fathers, one government official and one hospital staff member, according to police.

In total, 1,483 children are suspected to be linked to eight hospitals. Sixty-two suspected children were found in one hospital alone; 19 were confirmed as part of the network, while 43 other cases are being investigated.

On Thursday, Bangkok Governor Chadchart Sittipunt said the Bangkok Metropolitan Administration (BMA) is cooperating with the Department of Provincial Administration and the Royal Thai Police to probe illegal Thai citizenship registrations. One BMA staff member has been dismissed so far.

The probe is focusing on cases where the father is Thai and the mother is a foreigner, or where the same father has children with multiple foreign women, he said. He also said each district runs the birth certification process differently. Some districts have only one official as a liaison with the hospital, which may increase the risk of corruption.