U.S. producer prices rose for the third month in a row in December, increasing by 0.2 percent on a surge in food prices and recording their largest year-on-year gain since October 2008, according to a government report on Wednesday.

The annual gain of 4.4 percent, though, was slightly below analyst expectations of a 4.5 percent increase. On a month-on-month basis, analysts polled by Reuters had anticipated monthly prices paid at the farm and factory gate to remain unchanged in December.

The Labor Department said core prices, which exclude food and energy, were steady in December. Analysts had expected a 0.1 percent gain.

(Reporting by Lisa Lambert, Editing by Chizu Nomiyama)