Tucked on a leafy street in Leblon, the seaside bastion of Rio De Janeiro elite, Antiquarius ranks among Brazil’s most exclusive restaurants. Well-heeled regulars frequent Antiquarius, which is decorated in faux-farmhouse style with landscape paintings and porcelain vases, and charges $68 for a stew of codfish in coconut-tomato sauce.

But while Antiquarius’s prices have long shocked many people here, the restaurant is now gaining notoriety for another reason. Inspectors raided it in Aug., finding more than 50 pounds of expired food like ham, endive and beef tripe in its kitchen, including more than 10 pounds of snails with an expiration date of July 2012.

The inspection in August was, according to the New York Times, one of several raids this year by officials seeking to improve the city’s restaurant standards as more visitors flock to Rio ahead of the 2014 World Cup and 2016 Olympics, both of which will be held here.

“Some restaurants think they will never be inspected, just because they are so chic and expensive,” said Cidinha Campos, director of Rio’s consumer protection agency, singling out an item on Antiquarius’s menu, grilled slipper lobster in beurre d’escargots, which costs about $78. The restaurant’s snail butter used in the recipe was also found to have expired, she said.

“Well,” Ms. Campos said, “even Antiquarius is not above the law.” She added that the restaurant, which serves dishes largely inspired by the cuisine of Portugal, Brazil’s former colonial ruler, could face a fine from about $200 all the way up to $3 million, depending on its explanation of its kitchen practices and the size of its revenues.