The Van Gogh Museum is disputing claims that a sketchbook, called one of the biggest art discoveries in France, belongs to Vincent van Gogh. The assertion came from French publishers, Le Seuil, during a press conference in Paris on Tuesday. The publishers said that 65 unpublished drawings by van Gogh were discovered in Arles, France in the archives of a hotel called Café de la Gare where van Gogh had stayed in the late 19th century. Le Seuil announced that “their authenticity is well established.”

The museum, located in Amsterdam, Netherlands, released a statement on Tuesday refuting Le Seuil’s authenticity claims after being subjected to questions about the sketches. The museum said they have been aware of the sketchbook “for some time” and their experts examined the drawings in 2008, 2012 and in 2013.

“Their opinion, based on years of research on van Gogh's drawings in the museum's own collection and elsewhere – the van Gogh Museum holds about 500 drawings by van Gogh and four of his sketchbooks – is that these album drawings are imitations of van Gogh's drawings,” the statement read.

The museum’s statement listed a number of reasons why they believe the drawings aren’t authentic, including the characteristic style of the works, the brownish ink used, topographical errors, the Café de la Gare’s ownership of the drawings and the unreliability of the notebook itself.

“Our researchers and curators are happy about every new work that can correctly be attributed to van Gogh, but on the basis of high-quality photographs sent to them of 56 drawings – out of 65 in total – they were of the opinion that these could not be attributed to Vincent van Gogh,” the statement continued.

According to Le Seuil, the works are believed to have been drawn during a tumultuous period towards the end of the artist’s life between 1888 and 1890. Some of the sketches include portraits of his friends Paul Gauguin and Pierre and Marie Ginoux, who owned the Café de la Gare where had stayed. The majority of the drawings portray the Provencal countryside around Arles.

The original drawings were not displayed at the press conference, but the publishers did launch a book with reproductions of the drawings called “Vincent van Gogh: The Lost Arles Sketchbook.” Le Seuil’s book with the reproductions will be published simultaneously in France, the U.S., Britain, Japan, Germany and the Netherlands on Thursday.