TOKYO (AFP, REUTERS) - A Tokyo medical school on Tuesday (Aug 7) admitted entrance test scores for female applicants were routinely altered to keep women out and apologised for the discrimination after a probe.

"We betrayed the public trust. We want to sincerely apologise for this," Tokyo Medical University managing director Tetsuo Yukioka told reporters as he bowed deeply.

"Society is changing rapidly and we need to respond to that, and any organisation that fails to utilise women will grow weak," said Professor Yukioka, who is the school's executive regent and chair of its diversity promotion panel.

Such alterations "should never happen", added Professor Keisuke Miyazawa, vice-president of the university, pledging that next year's entrance exams would be fair, without giving further details.

The senior school officials pledged to "sincerely" consider their response, such as possible compensation. However, they said they had been unaware of the manipulation.

Japanese media last week reported that the university had for years been lowering the scores of female applicants in order to keep the proportion of women in the school at 30 per cent or lower.

Initial reports suggested that the practice dated to 2011, but a probe conducted after the reports found the alterations started as early as 2006, Kyodo News reported on Tuesday.

The scandal was uncovered by investigators looking into claims that the university padded the scores of an Education Ministry bureaucrat's son to help him gain admission. Local media said other instances had been discovered where individual entrance test scores were revised upwards, suggesting favouritism.

But female applicant test scores were lowered across the board.

The manipulation was "nothing but discrimination against women", said one of the lawyers hired by the university to investigate the alterations, speaking at a press conference on Tuesday.

The lawyers said the score of the bureaucrat's son, and the scores of several other men, were boosted "unfairly" - by as much as 49 points in one case.

They also concluded that scores were manipulated to give men more points than women and thus hold down the number of women admitted, since school officials felt they were more likely to quit the profession after having children or for other reasons.

"This incident is really regrettable - by deceptive recruitment procedures, they sought to delude the test takers, their families, school officials and society as a whole," lawyer Kenji Nakai told a news conference.

"Factors suggesting very serious discrimination against women was also part of it," added Mr Nakai.

The investigation showed that the scores of men, including those reappearing after failing once or twice, were raised, while those of all women, and men who had failed the test at least three times, were not.

The lawyers said they did not know how many women had been affected.

In 2018, the ratio of women accepted to the medical school after the first round of tests was 14.5 per cent, compared with 18.9 per cent for men.

In the second and final test stage, just 2.9 per cent of female applicants were admitted, compared with 8.8 per cent of male applicants.

The story has caused outrage in Japan, with women's empowerment minister Seiko Noda calling the practice "disturbing".

"It's extremely disturbing if the university didn't let women pass the exams because they think it's hard to work with female doctors," public broadcaster NHK quoted her as saying on Tuesday.

Japanese women are highly educated in general but the country's notoriously long work hours force many out of the workplace when they start families.

Prime Minister Shinzo Abe has made "womenomics" - or boosting women's participation in the workplace and promoting women to senior positions - a priority, but the pace of progress has been slow.