TOKYO >> A Japanese medical university has systematically discriminated against female applicants because women tend to quit as doctors after starting families, causing hospital staffing shortages, media reports said today.

The Yomiuri newspaper said Tokyo Medical University has manipulated the entrance exam results of women since about 2011 to keep the female student population low. Quoting unidentified sources, it said the manipulation started after the share of successful female applicants reached 38 percent of the total in 2010.

Other Japanese media, including NHK public television and Kyodo News, also reported the exam manipulation. Quoting unnamed sources, NHK said female applicants’ scores were slashed by about 10 percent in some years.

The allegation surfaced during the school’s probe of a separate scandal in which its former director was accused of granting admission to the son of a top education bureaucrat in exchange for a favor.

The school’s public affairs department said officials were surprised by the Yomiuri report and had no knowledge of the reported manipulation. It promised to look into the matter.

Yoshiko Maeda, head of the Japan Medical Women’s Association, said it was astonishing that women in Japan are still being stripped of their right to seek entry to the medical profession.

“Instead of worrying about women quitting jobs, they should do more to create an environment where women can keep working,” Maeda said in a statement on the group’s Facebook page. “And we need working style reform, which is not just to prevent overwork deaths, but to create a workplace where everyone can perform to the best of their ability regardless of gender.”

In Japan, many women are college graduates but face discrimination in hiring and pay. Long working hours and lack of support in child rearing from their husbands often force them to give up their careers. As Japan’s population ages and birth rates remain low, many workplaces including hospitals are chronically short staffed.

Earlier this year, a Health, Labor and Welfare Ministry panel urged medical institutions to allow more flexible working environments and support for female doctors so they can return to work after maternity leave and balance work and family.

While women account for more than 40 percent of the overall workforce, the share of female doctors who have passed the national medical exam has plateaued at around 30 percent for more than 20 years. The slow progress in medicine has prompted speculation among some doctors about possible widespread interference in the school admissions process.

“Entrance exams that unfairly discriminate against women are absolutely not acceptable,” Education Minister Yoshimasa Hayashi told reporters. He said the ministry will decide on its response after receiving the results of an investigation from the school.

In Japan, medical graduates usually end up working at school-affiliated hospitals.

According to the Yomiuri, the school started to restrict the portion of females in each class to about 30 percent by manipulating the test scores to get more women to fail.

Admissions records released to The Associated Press by the school show the percentage of women who passed the entrance exam rose from 24 percent in 2009 to 38 percent in 2010. The figure has since stayed below that level until decreasing to 18 percent this year. The ratio of female applicants who were accepted this year was 2.9 percent, compared to 8.8 percent for men.