The Labor Department yesterday barred Firestone Tire & Rubber Co., the nation's second largest rubber maker, from doing any more business with the government unitl it complies with federal antidiscrimination orders.

Firestone has annual sales totaling $5.3 billion and an estimated $40 million worth of direct government contracts. Department officials believe it is the largest firm so far to be found in violation of Federal Executive Order 111246, which prohibits race and sex discrimination by government contractors.

Ironically, Uniroyal Inc., the nation's third largest rubber manufacturer, held that "honor" last year, when the government canceled some $36 million worth of contracts because of alleged noncompliance with federal antidiscrimination orders. Uniroyal settled its case last Oct. 23 by agreeing to pay $5.2 million in back wages to 750 women at its Mishawaka, Ind., plant.

Firestone is not being accused of race or sex discrimination per se. Instead, in the ruling handed down by Labor Secretary Ray Marshall, the company is charged with failure to implement an acceptable affirmative action program to increase the number of minority and women employes among the 650 workers at its Firestone Petrochemical Center in Orange, Tex.

However, Firestone officials yesterday said the department's ruling was at best arbitrary -- based on "an unreasonable interpretation of a technicality in the law, and not any pattern of discrimination as such."

"We have had an affirmative action program in Orange for more than 10 years, and about 25 percent of the 650 employes there are women or minorities," company officials said in a prepared response to the department's ruling. "This proportion reflects the success of our equal employment opportunity efforts and indicates our compliance with equal employment opportunity requirements," the Firestone officials said.

A company spokesman said Firestone will file its appeal of Marshall's ruling in the U.S. District Court at Beaumont, Tex. "We believe we have a good case," the spokesman said, pointing out that a department admnistrative law judge ruled last May that the department had failed to prove its allegations against Firestone.

However, the administrative law judge's decision was overturned by Marshall's ruling.

Marshall's orders delcares that all present government contracts and subcontracts with Firestone be terminated, canceled or suspended and that the company be held ineligible for further contracts or subcontracts until it can "satisfy" the government that it is making earnest efforts to correct the alleged sex-race imbalance in its affected work force.

However, individual government agencies such as the Defense Department have the right to challenge any contract cancellations or suspensions affecting national security, department spokesman Ferrand said.