A teenage Catholic girl who converted to Islam has been banned from attending a school in the eastern Paris suburbs because her skirt is too long.

The headteacher of the school in Montereau-Fault-Yonne told the 16-year-old that the length of her skirt meant that it was an “ostentatious religious symbol” – something forbidden in state schools in France since 2004.

A meeting will be held at the school with the pupil’s parents to try to resolve the dispute, following a rash of similar incidents in other French schools last year.

Long skirts if worn as a fashion statement are allowed in French schools. Long skirts worn as sign of allegiance to Islam – or any other religion – may fall foul of the 2004 law which enforces the principle that state schools are secular.

The council of state, the final arbiter of the meaning of French laws, has been asked to rule on the “long skirt” issue but has not yet done so.

The girl has been named only as K De Sousa, French of Portuguese origin. She converted to Islam, with the blessing of her family, a year ago. The French education system investigated whether she was part of a radical Islamic movement and decided she was not.

Her mother Marie-Christine de Sousa told French magazine L’Obs: “My daughter respects the law. I respect her religion. Until now, the school has made no comment on the way she dresses.

“Apart from chattering in class, she has no problems and doesn’t say much about her conversion. People shouldn’t jump to conclusions.”

K De Sousa wears a headscarf in public but takes it off when she reaches school, as the 2004 law demands. The law was enacted after a series of rows in French schools about the wearing of headscarves. It was broadened to ban all “ostentatious religious symbols” to avoid seeming to stigmatise Islam.

A handful of schools in France have begun to interpret long skirts won by Muslim girls as a religious symbol. Most do not.

The education board covering K De Sousa’s school admitted that dialogue between the school and her family had “not gone entirely serenely”.

“Talks will resume on Monday,” a spokesman said.