U.S. diesel prices were up nearly 2 cents per gallon from a week ago and more than 6 cents per gallon compared to a year earlier, as crude oil prices rose to their highest since early July.

Oil producers participating in a supply-reduction agreement cut output in July by 9% more than called for, reports Reuters, and Iran’s crude oil exports have fallen amid U.S. sanctions against the country. Reuters reports that risks of supply disruptions from places such as Venezuela, Africa and Iran triggered expectations of a tightening global oil market.

Crude oil futures ended Monday, August 27, 15 cents higher on the New York Mercantile Exchange at $68.87 a barrel. Oil prices had their best week since June last week, climbing more than 5% on a larger-than-expected drop in U.S. inventories, reports the Wall Street Journal.

The U.S. Department of Energy’s fuel price report for the week ending Aug. 27 showed the national average retail price of $3.226 was up 1.9 cents from the previous week and 6.21 cents from last year.

The highest price, $3.945 in California, is up 1.6 cents from last week but 95 cents from last year. The lowest prices were found in the Gulf Coast region at $3.004 per gallon, up 2.3 cents from last week and 57.6 cents from last year.

While diesel prices were up in all regions of the country compared to last week and last year, gasoline prices were up from a year ago but actually fell slightly in many regions of the country.

The national average price for gasoline of $2.827 per gallon was up .6 cents from last week and 42.8 cents from last year. The highest prices, on the West Coast at $3.310 per gallon, were up .03 cents from last week and 40.7 cents from last year. The lowest prices, $2.569 in the Gulf Coast region, was up .01 cents from last week and 41.3 cents from last year. However, gasoline prices fell from the previous week in the East Coast region and in the West Coast minus California.