BURLINGTON, Vt. - Sen. Bernie Sanders (I-VT) has called for a federal investigation into unusually high gasoline prices in the greater Burlington area compared to other parts of Vermont, New England and other areas throughout the country.

In a letter to U.S. Attorney General Eric Holder and Federal Trade Commission Chairman Jon Leibowitz, Sanders wrote: "I am writing to urge the Oil and Gas Price Fraud Working Group and the Federal Trade Commission to conduct a joint investigation to determine why gasoline prices in greater Burlington, Vermont, (Chittenden, Grand Isle and Franklin Counties) are substantially higher than other parts of the state, New England, and similar areas throughout the country." Sanders spoke with the FTC chairman about the investigation on Monday afternoon.

During one month, prices in greater Burlington fell 15 cents a gallon ?" from $3.84 to $3.69 for regular unleaded. That??s the lowest price reduction in any of the 15 metro regions throughout New England, according to AAA??s Daily Fuel Gauge Report data. The average price drop at these New England metro areas for a gallon of regular unleaded was 25.9 cents during the month examined.

Greater Burlington, as defined by AAA, includes Chittenden, Grand Isle and Franklin Counties. The analysis conducted by Sanders?? office used the AAA data for monthly gas price changes with the month ending June 25. During this same time period, prices fell as much as 34 cents per gallon in Manchester, N.H.

In his letter Sanders also asked the Justice Department and Federal Trade Commission to determine whether or not high prices in Chittenden County were related to the fact that the four largest gas station companies in the county control 67 of the 115 filling stations, or 58% of the total.