New York State Attorney General Letitia James accused New York City of an $810 million fraud scheme involving taxi medallions Thursday, arguing that city officials artificially inflated medallion prices before auctioning them off.

In a notice of claim addressed to New York City Comptroller Scott Stringer, James said the city’s Taxi and Limousine Commission concealed internal analysis showing that the price of taxi medallions had outstripped their value, among other offenses.