More than half the paintings owned by a southern French museum are worthless fakes, and authorities fear more forgeries may be on display at other public galleries.

The small museum in Elne, dedicated to local artist Etienne Terrus, a contemporary of Henri Matisse, learned that 82 of its 140 works are fakes after art historian Eric Forcadea raised the alarm.

Forcadea noticed while helping to prepare an exhibit that some of the paintings attributed to Terrus featured buildings built after his 1922 death.

The state-owned Terrus Museum had a committee of experts inspect the works and concluded that many were not been painted by the Elne-born artist.

Roughly $170,000 was paid for the phony oil paintings, watercolors and drawings over the past few decades. Two local groups raised money to buy others, and more were donated to the museum run by the local city hall.

“It’s a catastrophe,” Yves Barniol, the mayor of Elne, near the Spanish border, told The Telegrah. “I put myself in the place of all the people who came to visit the museum, who saw fake works of art, who paid an entrance fee. It’s intolerable and I hope we find those responsible.”

Barriol said the city recently invested $365,000 refurbishing the museum. “We will continue to promote local art.”

The municipality filed legal complaints for forgery and fraud, which can help spur a broader investigation. Police seized the fakes and are trying to trace the forgers and dealers who sold them.

Detectives suspect that other museums may also contain large numbers of forged works attributed to southern French artists. “We know there have been a lot of forgeries circulating and we believe a well-organized network was behind this,” a source told the Telegraph.

Art experts estimate that at least 20 percent of paintings owned by major museums across the world may not be the work of the purported artists.