French fashion house Chanel has threatened to close its historic Grasse perfumery in response to a planned train line in the area.

In an open letter, Chanel has threatened to close the perfumery, which is responsible for the floral notes in the iconic fragrance Chanel No. 5.

“The construction of a viaduct and the regular passage of high-speed trains over these fields of flowers would force Chanel to cease supporting its artisanal activities in the region,” Chanel said in the letter, according to Vogue UK.

In the statement, Chanel says the flowers harvested in the area are “unique and exceptional and indispensable for the creation of Chanel perfumes.”

Chanel No. 5 created in 1921 and made world-famous by blond bombshell Marilyn Monroe — relies on extracts of “Grasse” jasmine and May rose that are cultivated in and around Grasse. The scent is said to have remained unchanged for decades. Chanel harvests May roses and jasmine flowers in the fields, a rumoured 1,000 jasmine flowers and a dozen May roses go into every bottle of Chanel No. 5, but that could change thanks to the ambitious French infrastructure plans.

Chanel has been supporting a campaign to put Grasse’s perfume-making area on UNESCO’s protected heritage list, and it successfully lobbied in 2009 to end a project to create a refuse centre near the flower gardens in Pegomas and the Siagne Valley.

The fragrance was created in 1921 by Coco Chanel who yearned for a “woman’s perfume with a woman’s scent”, and it quickly came to symbolise, along with her clothes designs, a new breed of emancipated, modern female. Chanel commissioned Ernest Beaux – who had been the perfumier to the Russian tsar – to push the boundaries of what was considered an acceptable scent for women to wear.

“I don’t want any rose or lily of the valley perfume; I want a more elaborate scent,” she famously said.

The proposed train route would reduce travel time between Marseilles and Nice by an hour but would directly affect Grasse farmers and Chanel.