A French museum dedicated to painter Étienne Terrus has discovered paintings it thought were by him were fakes.
The Terrus museum in Elne in the south of France discovered 82 works originally attributed to the artist were not painted by him.
More than half the collection is thought to be fake. The paintings cost about €160,000 (£140,000).
Staff at the museum were not aware of the forgeries until a visiting art historian alerted them.
The council in Elne bought the paintings, drawings and watercolours for the museum over a 20-year period.
Eric Forcada, an art historian, contacted the museum in the town near Perpignan several months ago to express his doubts about the authenticity of the paintings.
The museum assembled a committee of experts from the cultural world, who inspected the works and concluded that 82 of them had not been painted by the Elne-born artist.
The news was announced on Friday as the museum opened after a renovation.
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In interviews on Friday, the mayor of the Pyrenees town, Yves Barniol, said the situation was “a disaster” and apologised to those who had visited the museum in good faith.
Terrus was born in 1857 and died in 1922 in Elne, although he lived most of his life in Roussillon, also in the Pyrenees. He was a close friend of painter Henri Matisse.
The town hall has filed a complaint against those who ordered, painted, or sold the fake paintings.
Local police are investigating the case, which they say could affect other regional artists too.