The Justice Department has sued to block Tribune Publishing Co.'s purchase of Freedom Communications newspapers.
Tribune owns the L.A. Times and Freedom owns the Orange County Register and Riverside County Press-Enterprise.
DOJ wants a temporary restraining order to prevent the sale.
DOJ says that the combination of the Times and the Register accounts for 98% of the newspaper sales in Orange County.
Justice said the purchase would give the combined company "a monopoly over newspaper sales in each county and allow it to increase subscription prices, raise advertising rates and invest less to maintain the quality of its newspapers.
“Newspapers continue to play an important role in the dissemination of news and information to readers and remain an important vehicle for advertisers,” said Bill Baer, assistant attorney general in the Antitrust Division. "The Antitrust Division is committed to ensuring that competition in this important industry is protected.”