A Japanese man who fathered at least a dozen babies using Thai surrogate mothers appeared in court via video conference on Tuesday, testifying in a case in which he is suing for paternal rights.

The lawyer for Mitsutoki Shigeta said that the Central Juvenile Court, where the case is being heard, will issue its ruling on Feb 20.

The publicity-shy Mr Shigeta, 28, currently lives in Japan, from where he testified. He reportedly hired many Thai women to bear his children in 2014.

The babies are being cared for under the watch of the Ministry of Social Development and Human Security until the case, which has drawn wide attention, reaches its conclusion.

It is not clear how many there are, with some reports saying dozens. Thai police have said DNA tests show 15 babies are definitely Mr Shigeta's.

The lawyer said Mr Shigeta wanted to have dozens of babies because he desired a large family and hopes for them to inherit his fortune in the future. Unconfirmed reports have said he has paid about US$500,000 on his surrogacy project - about 16.25 million baht.

At Tuesday's hearing, Social Development and Human Security Ministry personnel took turns testifying in court.

One of them said ministry staff went to Cambodia and Japan to visit places where the man intends to have his children raised and that "everything looks good."

According to local media, Mr Shigeta and some Thai surrogate women initiated a lawsuit against the ministry in January 2015, alleging that it violated their rights.

Previously, surrogacy was not strictly regulated in Thailand. Many foreigners turned to it for surrogates, drawn by both the relatively cheap cost and high-quality healthcare available in the country.

But it became a hot issue following a string of scandals, including the one involving Mr Shigeta and another involving an Australian couple who abandoned a surrogate-born baby with Down's syndrome and just took home his healthy twin sister.

In 2015, the law was changed to ban commercial surrogacy.

Now only couples of at least one Thai partner can access the country's surrogacy services. In the case of marriages between people of mixed nationalities, they must have been legally married for at least three years.

The surrogate mother must be a Thai citizen over the age of 25 who is preferably a blood relative but is neither a parent nor a daughter of the couple. She must have given birth before and she cannot receive any direct fees for being a surrogate.