Fewer than 60 percent of child consultation centers in Japan mediated "special" adoptions of children aged below 6 in fiscal 2013 due to staff shortages, a health ministry report showed Thursday.

A major purpose of the centers is to allow abused children or children who cannot be raised by their own parents for various reasons to be raised by another family. But only 57.9 percent, or 114 of the 207 centers across Japan, said they entrusted such children to registered foster parents in the business year that ended in March 2014, according to the survey by a ministry research team.

Unlike the case of regular adoptions, where legal connections with biological parents are retained, special adoptions allow the adopted children, who are under 6, to be treated as the biological children of their foster parents, erasing the previous legal ties.