Tyson Foods Inc., the nation's largest meat producer and processor, was indicted yesterday with six employees on charges that it conspired to smuggle illegal immigrants across the Mexican border to work in its processing plants. The 36-count indictment, which was unsealed at Federal District Court in Chattanooga, Tenn., accuses Tyson of arranging to transport illegal immigrants across the border and of helping them to get counterfeit work papers for jobs at more than a dozen Tyson poultry plants. The government said it was the largest case brought against a major American company involving the smuggling of immigrants. The indictment said that six Tyson employees, including two executives, participated in the actions and that the company engaged in the practices to cut costs, meet production goals and to maximize profits. The company could face sanctions and large fines if found guilty; the workers could face prison terms.