A DNA test of a Japanese man embroiled in a surrogacy scandal in Thailand shows that he is the biological father of at least 15 babies, police said Wednesday.
But his motives remained a mystery two weeks after the discovery of nine babies in a Bangkok apartment triggered a human trafficking probe.
The alleged father, who is reported by Japanese media to be the son of an IT millionaire, has left Thailand but voluntarily sent the DNA sample to try to clear his name.
"It is confirmed that he is the father of all the babies -- the 15 babies that we checked," Thai police doctor Lieutenant General Jongjate Aojanepong told AFP after the preliminary result.
The authorities still hope that the man will return to Thailand to help with the investigation, police Lieutenant General Kokiat Wongvorachart told reporters.
"If he comes, we will get clear information from him," he added.
Asked about the content of a written explanation submitted by the Japanese through his lawyer, Kokiat said: "He said he can take care of them. He wants to have children."
"From our checks of the living conditions of the babies, so far there has not been any abuse or involvement in human trafficking or unlawful use of the babies," he added.
He said Thailand would seek help from foreign police experts to confirm the preliminary DNA test result.
The case is the latest twist in a widening surrogacy scandal initially triggered by accusations that an Australian couple abandoned a baby born with Down's syndrome with his Thai surrogate mother -- but took his healthy twin sister.
Paid surrogacy is illegal in Thailand. The military rulers have vowed to introduce a new law that could result in 10 years' imprisonment for anyone found guilty of involvement in the trade.
Australia has asked Thailand to make "transitional arrangements" to help any of its citizens who have already entered into surrogacy agreements.
In the case of the Japanese man, the surrogate mothers have said they did not use their own eggs, according to police.