Female flight attendants are furious that Air France will require them to wear headscarves and loose clothing in Tehran when service from Paris to Iran's capital resumes later this month, union representatives say.

Multiple flight crew unions are fighting back against the rules, with at least one reaching out to a government minister in hopes that she would intervene.

The headscarf requirement and clothing limitations are "true threats to their dignity," the Union des Navigants de l'Aviation Civile (UNAC) wrote in a letter to Laurence Rossignal, France's minister for women’s rights and families, Friday.

Another union, Syndicat National du Personnel Navigant Commercial (SNPNC), also denounced the provisions in a statement, calling them "an attack on freedom of conscience and individual freedoms, and invasion of privacy."

Union representatives have asked Air France to make service on flights to Tehran voluntary for female crew members who do not want to wear headscarves, without repercussions related to pay or schedules.

Women are required to cover their hair in Iran; meanwhile in secular France, hijabs and full body veils are banned.

Air France is set to resume service to Tehran on April 17 after an eight-year break. The service was initially cut as part of international sanctions related to Iran's nuclear program. Following the 2015 nuclear deal struck between Iran, the U.S., France and several other countries, Air France announced it would fly once again to the tourist-hungry country.

Specifically, Air France's modesty rules require women to wear pants during the flight from Paris to Tehran and a loose fitting jacket and headscarf when they exit the plane. Those that don't comply could be penalized, Christophe Pillet, an SNPNC spokesperson told Agence France-Presse.

“It is not our role to pass judgment on the wearing of headscarves or veils in Iran," Flore Ariighi, head of the UNAC told the Telegraph. "What we are denouncing is that it is being made compulsory. Stewardesses must be given the right to refuse these flights.”

Air France told the AFP that the headscarf rule was not new. It was in place before service to Tehran was cut in 2008.

"Iranian law requires that a veil covering the hair be worn in public places by all women on its territory," the airline said. "This obligation, which does not apply during the flight, is respected by all international airlines which fly to Iran."

According to the union letter to the government minister, Air France also asked its female flight attendants to refrain from smoking in public. Male attendants were not given the same advisory.

Air France has not responded to Mashable's request for comment.

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