The cost of on-highway diesel moved slightly higher over the past week, gaining one-tenth of a cent for a national average price of $3.920 per gallon. The Department of Energy's weekly pump price survey shows diesel's average price is now 10.3 cents higher than it was one year ago.

Prices increased in all sections of the country except the East Coast as a whole, where it's down two-tenths of a cent from last week; the Lower Atlantic region, where it's down six-tenth of a cent, and the Midwest, where it's also six-tenths of a cent lower than last week.

Increases were modest across the country, with the highest increase coming on the West Coast. Prices there rose two cents over last week.

Other than California ($4.138), New England had the highest prices at $4.107, followed by the Central Atlantic region and the West Coast at $4.073.

The Gulf Coast region reports the lowest average price at $3.816.

All regions are higher than their year-ago averages.

The average cost of regular grade gasoline held at $3.704 again this week, but it's 20.8 cents higher compared to the same week a year ago.

Prices moved higher in all parts of the country except the Midwest and the Gulf Coast, where they fell 2.2 and 1.1 cents respectively from last week.

Prices range from a low of $3.483 in the Gulf Coast region to a high of $4.036 in the West Coast region.

Adequate U.S. crude supplies and speculation that the escalating violence in Iraq is unlikely to disrupt supply kept oil prices to their lowest price in the previous two weeks. It's closed in New York on Monday at $105.37 a barrel.