The State Council, France's highest court for complaints against government authorities, said it had rejected a motion by an association for an injunction against the ban decreed by the government last month, saying it was not discriminatory towards Muslims.
President Emmanuel Macron's government announced last month it was banning the abaya in schools, saying it broke the rules on secularism in education that have already seen Muslim headscarves banned on the grounds that they constitute a display of religious affiliation.
But an association representing Muslims filed a motion with the State Council, France's highest court for complaints against state authorities, for an injunction against the ban on the abaya and the qamis, its equivalent dress for men.
The association argued the ban was discriminatory and could incite hatred against Muslims, as well as racial profiling.
The State Council has been examining the motion, filed by the Action for the Rights of Muslims (ADM), since Tuesday, and ruled in favour of maintaining the ban on Thursday.
France's Council of the Muslim Faith (CFCM), established to represent Muslims before the government, warned that banning the abaya could create "an elevated risk of discrimination" and said it was considering putting its own complaint before the State Council.
ADM's lawyer, Vincent Brengarth, argued during the court hearing that the abaya should be considered a traditional garment, not a religious one.
He also accused the government of seeking political advantage with the ban.
ADM president Sihem Zine said the rule was "sexist" because it singles out girls and "targets Arabs".
But the education ministry said the abaya made its wearers "immediately recognisable as belonging to the Muslim religion".
French schools sent dozens of girls home for refusing to remove their abayas – a shoulder-to-toe over-garment – on the first day of the school year on Monday.
Nearly 300 schoolgirls defied the ban, Education Minister Gabriel Attal said.
Most agreed to change garments but 67 refused and were sent home, he said.
Around 10 percent of France's 67 million inhabitants are Muslim, according to official estimates.
Most have origins in northern African countries Algeria, Morocco and Tunisia, which were French colonies until the second half of the 20th century.
(FRANCE 24 with AFP)