Federal prosecutors say 22 people have been charged with $13 million in food stamp fraud centered at a Miami-area flea market.

U.S. Attorney Wifredo Ferrer said Wednesday the scheme used electronic benefit cards at locations authorized to accept Supplemental Nutrition Assistance Program benefits. The cards would be swiped in exchange for cash payments far less than the amount the store owners would bill to the program.

Most of the fraudulent retailers were located at the Opa-locka Hialeah Flea Market, but they also include a fish delivery business and a convenience store. Ferrer says many locations actually sell no food.

Those arrested face maximum prison terms of 20 years for each count of wire fraud and wire fraud conspiracy, as well as five years for food stamp fraud.