PARIS — A group of leading French architects have denounced a plan to renovate the Gare du Nord, one of Paris’s main train stations, calling the designs that would turn the station into a glassy, mammoth, restaurant-filled shopping mall “indecent,” “absurd” and “unacceptable.”

The plan for the Gare du Nord, the terminus for the Eurostar train from London and the largest station in Europe, would cost 600 million euros, about $660 million, and force commuters and travelers to go through a platform lined with shops before getting to the train platforms, in much the way that airports route passengers through duty-free shops.

“This means: more distance to travel, significantly increased access times,” the experts wrote in an open letter published in Le Monde on Tuesday. They called the plan to triple the station’s surface area and saturate it with shops, restaurants and cafes in an area already buzzing with them a “serious offense” to users of transport.

Among the 19 signatories of the letter were the award-winning architect Jean Nouvel, as well as other renowned architects, historians and urban planners from Britain, France and the United States.