Attorney General Benjamin R. Civiletti yesterday gave qualified approval to the partial merger of Chattanooga's two daily newspapers, accepting the newspapers' contention that a joint operating plan was the only way to preserve their two independent editorial voices.

The Chattanooga Times, which lost $2.7 million in the past four years, said it would be forced to closed unless it could turn its printing and business operations over to the more profitable Chattanooga News-Free Press.

The two newspapers have been archrivals for years.

Under the plan, the newspapers' reporting and editorial staffs would remain separate and independent. The Times also agreed to drop its Sunday newspaper, leaving that field to The News-Free Press.

The two newspapers had asked the Justice Department to approve the joint agreement under terms of the Newspaper Preservation Act, which provides immunity against antitrust suits arising from such mergers. The International Typographical Union has opposed the joint operating plan on behalf of the Times' printers, who stood to lose their jobs if it went into effect. The News-Free Press is a non union newspaper.

But on May 12, before Civiletti had ruled on the request, the two papers combined printing operations, putting into effect some but not all of their original merger plan. The Times said it was losing money too rapidly and could wait no longer.

In his ruling yesterday, Civiletti said that The Times is a "failing newspaper" and a partial merger of the two newspapers comes under the protection of the Newspaper Preservation Act. But this immunity doesn't extend to the combined printing operation that began on May 12, before the department's ruling, Civiletti added.

Civiletti said he will determine later which parts of the combined business and printing operations qualify for antitrust immunity.