Ethanol bears some of the blame for last year's rising food prices, but oil and electricity bear more, according to a new congressional study of the food-versus-fuel debate.

The ethanol industry and its critics have been locked in a fierce argument over whether the alternative fuel, typically made from corn, pushes up food prices. Thursday's report from the Congressional Budget Office gives some ammunition to each side.

Researchers found that ethanol production was responsible for 10 to 15 percent of the increase in food prices between April 2007 and April 2008. As new ethanol biorefineries opened across the country, corn prices rose, causing a wave of price increases for everything from corn-syrup sweeteners to meat from animals fed with corn.

MBA BY THE BAY: See how an MBA could change your life with SFGATE's interactive directory of Bay Area programs.

But ethanol production wasn't the only culprit.

Between 22 and 36 percent of the overall increase in food prices can be traced to the rising cost of traditional energy sources such as gasoline, diesel and electricity, according to the report. Virtually every step of food production - from planting to transportation to processing - consumes fuel or electricity. The period covered by the report also saw record-breaking oil and gasoline prices.

Both sides of the ethanol debate claimed vindication Thursday.

"The report released by the Congressional Budget Office confirms what we've known for some time - the impact of ethanol production on food prices is minimal, and that energy was the main driver in the rise of food prices," said Tom Buis, chief executive of Growth Energy, an ethanol-industry association.

"Today's Congressional Budget Office numbers once again remind us of the unintended negative consequences associated with our nation's current policies which promote and mandate the conversion of massive amounts of corn and other food crops for biofuels production," read a joint statement from the Grocery Manufacturers Association, the American Meat Institute, the National Turkey Federation and the National Council of Chain Restaurants.