A Hokkaido man in his 70s plans to file a lawsuit seeking damages from the government over his forced sterilization at around age 20 under the 1948 eugenic protection law, sources said Thursday, as a related investigation unearthed documents showing children aged 15 and below — including one as young as 9 — were also sterilized under the law.

The revelations follow a lawsuit filed against the state by a woman in her 60s in Miyagi Prefecture on Jan. 30, seeking ¥11 million in damages over her forced sterilization when she was a teenager.

Japan’s now-defunct eugenic protection law authorized the sterilization of people with mental disabilities and illness or hereditary disorders to prevent births of what were feared would be “inferior” offspring. It also allowed for forcible abortions without the consent of the individuals or their relatives.

But the 1953 notification had limited the forcible removal of reproductive organs to only cases where there was “a possibility of bearing a baby.”

The most recently identified records, released Wednesday, show that at least 13 prefectures documented the sterilization of children aged 15 and below due to mental disabilities and other reasons, with the youngest having been aged 9 at the time of the surgery.

This latest find raises suspicions that sterilization may have been forced on young girls despite stipulations in the law against such surgeries being conducted on those who had no possibility of becoming pregnant.

According to a tally by Kyodo News, papers listing individual names of people believed to have been subjected to sterilization have been found in 23 prefectures. So far there are records involving 3,402 men and women, with the oldest having been 57 years old.

Referring to the cases involving children, Keiko Toshimitsu, a visiting bioethics researcher at a Ritsumeikan University research center, said “it would be surprising if such sterilizations were implemented widely.”

“Girls would have had to undergo abdominal surgeries, which are great physical burdens. I suspect that the operations were conducted based on extreme discrimination and prejudice,” Toshimitsu added.

In 2016, the U.N. Committee on the Elimination of Discrimination against Women recommended that Japan adopt “specific measures aimed at providing all victims of forced sterilizations with assistance to access legal remedies and provide them with compensation and rehabilitative services.”

The state has not apologized or provided compensation to the around 25,000 people who were sterilized under the now defunct law, saying it was legal at the time. Of the total, 16,500 people are believed to have undergone surgery without their consent.

While the eugenics protection law was scrapped in 1996 and replaced by the maternal protection law on abortion, human rights infringements under the eugenic law have drawn renewed attention recently, as in the lawsuit filed in January by the woman in Miyagi Prefecture at the Sendai District Court.

The filing by the woman, who has not disclosed her name, is the first such suit over forced sterilizations in Japan, and asserts that the state has failed to legislate for relief measures despite serious human rights infringements. She also claims that the 1948 law denied human equality and the right to pursue happiness and was therefore unconstitutional.

In the wake of that lawsuit, bar associations set up call centers in Sapporo and four other cities on Feb. 2 and urged others to join efforts to address the issue. The Hokkaido man currently planning to file his lawsuit was among several people who contacted the call centers, according to lawyers.

The man, who was about 20 when he was allegedly sterilized on grounds of having a mental disorder, has said he was unable to refuse the surgery at the time and wants the state to admit to its mistake, they said.

He intends to file the lawsuit with the Sapporo District Court after checking if the Hokkaido Prefectural Government has kept records on his sterilization.

The prefectural government said Monday it has records on 1,129 people who were sterilized under the controversial law, the youngest being an 11-year-old girl.

By prefecture Hokkaido is said to have the largest group, with 2,593 people believed to have been forcibly sterilized under the program.