As McDonald’s Holdings Co. (Japan) reels from a string of food safety incidents, authorities in Kagoshima Prefecture revealed Thursday they a report was received in August last year about a metal fragment found in french fries sold at one of the burger chain’s stores.

The prefecture said health authorities in Aira received a letter on Aug. 22 containing the fragment and claiming it was found in fries sold on Aug. 3.

Authorities inspected the store on Aug. 26 and issued a verbal warning.

According to prefectural officials, McDonald’s Japan later reported that the metal piece was highly unlikely to have found its way into the fries during production or preparation, adding that analysis of the fragment showed it was likely used for dental fillings.

McDonald’s Japan apologized Wednesday for recent incidents in which pieces of plastic or vinyl were found in food sold at several locations across the country.