A Japanese teenager who claims her public high school repeatedly forced her to dye her naturally-brown hair black or be banned from attending school, is suing the government of Osaka.

The 18-year-old girl said her mother informed Kaifukan School in Habikino city upon her enrolment that she was born with brownish hair, as the school had a policy banning hair colouring, in a lawsuit filed in Osaka District Court.

Educators, however, instructed her to colour her hair black, telling her repeatedly that the dye job was insufficient and forcing her to "either dye the hair black or quit school", the Kyodo news agency reported, citing the lawsuit.

The girl has not attended school since September 2016, suffered pain and irritation from the hair dye, and is seeking damages of about 2.2 million yen (£14,700), local media reported, adding that Osaka prefecture is asking the court to reject the claim.

Masahiko Takahashi, head of Kaifukan School, said he could not comment directly on the case, but noted the school's policy prohibiting students from dyeing or bleaching hair. He declined to say whether it was permissible to dye brown hair to black.

The girl could not be reached for comment.

In Japan, where conformity is the cultural norm, many schools have strict rules about hair colour, accessories, make-up and uniforms, including the length of skirts for girls.