Thai authorities say the surrogate mothers of 13 babies fathered by a Japanese businessman have sued the government ministry that took custody of their children.

The Social Development and Human Security Ministry took 13 babies into custody last year after an investigation involving the man alleged to have had at least 16 babies via surrogates.

Ministry official Suwanna Pinkaew said Wednesday the women launched a lawsuit against the ministry in December after filing requests to get back the children.

She said social services were evaluating the circumstances and the women's readiness before reaching a conclusion on the issue.

Thailand's interim parliament initially approved a bill banning commercial surrogacy in November after a string of scandals surrounding the largely unregulated business.