Tribune Co.’s December newspaper ad revenue fell 4.5 percent to $333.2 million, the company reported Thursday, reflecting a 9.6 percent slump from national advertising that was blamed on weak ad sales at the Los Angeles Times, the Chicago-based company’s largest paper.

The company’s total December revenue fell 6.1 percent, to $539 million, compared with the previous year.

Full-run ad volume at the Times plunged 13.9 percent from December of last year. In addition to the Times and Newsday, Tribune owns its namesake paper in Chicago.

Tribune’s local automotive-classified ads continued to slide, with revenue falling by 16 percent. Classified advertising revenues rose 2.5 percent due to gains in help wanted and real estate, which rose 13 percent and 21 percent, respectively.

Circulation revenue slipped 3.5 percent. Its interactive ad revenue jumped 33 percent, and the company saw a slight 2.5 percent increase in classifieds.

The Chicago-based company’s publishing revenues slipped to $413 million in December, compared to $431.2 million a year earlier. Nearly $6 million of the decline was due to the timing of the Christmas holiday on Sunday and the aftermath of Hurricane Wilma in South Florida, Tribune said.