SANTA ANA, Calif. (AP) - The Tribune Publishing Co. says federal regulators suing over its proposed purchase of bankrupt Orange County Register and another newspaper have an antiquated understanding of the industry in the digital age.

SANTA ANA, Calif. (AP) The Tribune Publishing Co. says federal regulators suing over its proposed purchase of bankrupt Orange County Register and another newspaper have an antiquated understanding of the industry in the digital age.

Tribune filed papers in U.S. District Court in Los Angeles on Friday.

The media giant won a bankruptcy auction earlier this week to purchase the Register and Press-Enterprise of Riverside for $56 million.

The U.S. Department of Justice says the merger would limit competition and harm readers and advertisers.

A bankruptcy judge must approve it at a Monday hearing and an antitrust expert says it's possible the federal action could scuttle the deal.

The sale would give Tribune control over the four largest daily newspapers in an area stretching from Los Angeles to the Mexican border.