PARIS (AFP) -- The open-air booksellers who line the Seine in Paris are refusing to be moved, despite concerns from French authorities over security for the opening of the Olympic Games on the river. The ceremony on July 26 next year will be the first in Olympic history to take place outside a stadium. Sources told AFP on Thursday the 200 "bouquinistes", who make up the largest open-air book market in Europe, were up in arms over a letter sent to them this week by the Paris police authority. The missive said it was "essential" to "remove" the boxes fastened to walls along the river banks in which the sellers stock and display second-hand books. The police want a perimeter where "access and movement of persons are regulated" to ensure the security of a "place or event exposed to a risk of acts of terrorism". Jerome Callais, head of the Paris Booksellers' Cultural Association, which represents 88 percent of bouquinistes, said they had "no intention of moving". "The official responsible for the Seine explained to us that we would be obstructing the view on the day of the ceremony," Callais said. "We're a major symbol of Paris. We've been here for 450 years!" he said. "To want to erase us from the landscape when the celebration of these Games should be a celebration of Paris seems a bit crazy." On Thursday, City Hall issued a press release assuring the booksellers of its support and acknowledging that their activity "forms part of the identity of the banks of the Seine". It estimated that 570 boxes, or 59 percent of the total, would be taken down. The city authorities are offering to pay for the removal and reinstallation of the boxes, as well as paying to repair any that are damaged in the process. They said this would be a "renovation" that would "support the booksellers' application to join UNESCO's intangible cultural heritage list." Callais said some of the boxes were "too fragile" to be moved, and estimated it would cost 1.5 million euros ($1.66 million) to renovate all of them.