HO CHI MINH CITY, Vietnam — The exhibition at the Fine Arts Museum in Ho Chi Minh City was billed as a triumphant homecoming for works by some of Vietnam’s most influential artists.
But Nguyen Thanh Chuong, a prominent artist himself, was stunned by what he saw.
Hanging on the wall was a painting he recognized as his own, a Cubist-inspired portrait he did in the early 1970s.
But instead of his name, the canvas bore the signature of one of Vietnam’s best-known artists, Ta Ty, and the date 1952. “I could not believe my eyes,” he said. “It made my hair stand on end.”
Mr. Chuong’s discovery set off a scandal that has rocked the Vietnam art world and highlighted an embarrassing truth: The Vietnamese art market, where prices of prewar paintings have recently broken the million-dollar mark, is rife with fraud.
“That remains one of the biggest challenges for the Vietnamese art market,” said Suzanne Lecht, an American who owns the Art Vietnam Gallery in Hanoi. “How do people know what is fake and what isn’t?”
Even esteemed Vietnamese art institutions, including major national museums, have showcased paintings they acknowledged were not authentic. Likewise, the auction houses Christie’s and Sotheby’s, as well as a consultant who worked for both of them, have sold works later dismissed by some experts as fakes.
Some of Vietnam’s greatest artists are enjoying a moment of increasing world attention, especially those who studied at the French-influenced Fine Arts College of Indochina before World War II. The best of them synthesize European post-Impressionist trends with classical Asian styles and subjects, and their work is commanding higher prices.
Vietnamese art remains a niche market globally but is surging in popularity at international auctions. In April, a late 1930s painting by one artist, Le Pho, sold for nearly $1.2 million at a Sotheby’s auction in Hong Kong, breaking the $844,000 record set by another of his paintings in 2014.
But artists and dealers complain that the proliferation of fakes is dragging down the value of Vietnamese art.
Vietnam’s nouveau riche, who have begun to pay high prices for local artists, are a prime target for unscrupulous traders. So are international buyers, whose faith that they are buying the genuine article is bolstered by the institutions that vouch for it.
The Fine Arts Museum in Ho Chi Minh City, where the disputed painting by Ta Ty, who died in 2004, was part of the exhibition “Paintings Returned From Europe,” rents its walls to private collectors, giving their paintings the imprimatur of the top museum in Vietnam’s largest city.
The 17 paintings in the exhibition belonged to Vu Xuan Chung, a Vietnamese art dealer who said he paid the museum about $1,300 to hold the 12-day event last year.
“A museum is the ultimate venue to validate a work of art,” said Colette Loll, founder and director of Art Fraud Insights, a Washington consulting firm.
After questions surfaced about the paintings, the museum quickly determined that none of the 17 paintings were created by the painters claimed by the exhibition. Museum officials apologized to the public and said they would hold the paintings for an investigation. But that never happened. Soon after, the museum quietly returned the paintings to their owner, Mr. Chung, who disputes the museum’s findings and says the paintings are authentic. He is now offering them for sale and recently sold one for more than $66,000.