The average price of a gallon of diesel fuel rose for the third week in a row, by 6.8 cents last week, according to weekly figures from the U.S. Department of Energy.

The DOE's Energy Information Administration reports the average retail price of on-highway diesel at $3.184 Monday. The highest prices were reported on the West Coast at $3.329, the lowest in the Gulf Coast region at $3.10.

Diesel is now at the highest level since October 27, 2008, and is 39.4 cents -- 14 percent -- higher than a year ago.

The price of gasoline is also up, the EIA reported, to $2.892 per gallon, up 2.7 cents from last week. That's 26.3 cents more expensive -- 10 percent -- than a year ago.

The American Trucking Associations noted in its weekly Fuel Line newsletter that a run-up in the
price of oil helped push diesel prices up. Early last week, the price of West Texas Intermediate crude oil increased to $87.81 per barrel, which was the highest level since the fall 2008.

However, crude prices fell Friday and again Monday, when they dropped below $85 per barrel on the New York Mercantile Exchange.