CHATTANOOGA, Tenn. (AP) -- A federal judge granted class-action status to a lawsuit that contends Tyson Foods Inc., the world's largest meat producer, depressed wages by hiring illegal immigrants at eight plants in Tennessee, Alabama, Indiana, Missouri, Texas and Virginia. 
   

 Howard W. Foster of Chicago, an attorney for Tyson employees, described the ruling as a "very big step," allowing him to seek damages for thousands of workers at the eight plants instead of just the four original plaintiffs.
   

 Roger Dickson of Chattanooga, an attorney for the Springdale, Ark., company, said he had not had a chance to read the judge's order and declined further comment.
   

 "This is a procedural ruling and not based on the merits of this case, which was actually dismissed by another judge back in 2002," Tyson spokesman Gary Mickelson said. "We remain confident our company will ultimately prevail."
  

 U.S. District Judge Curtis L. Collier's order, issued Tuesday, schedules a Jan. 29 conference with lawyers. It is expected he will set a trial date then.
   

 A federal jury in March 2003 acquitted the company and three former managers of conspiring to hire illegal immigrants from Mexico and Central America for low-wage production jobs to boost profits. Two former Tyson managers who made plea deals were sentenced to one year each of probation.
    

The acquittal dealt a setback to the government's strategy of enforcing immigration laws by going after big business.
   

 Prosecutors in the Tyson case relied mostly on tapes of secretly recorded conversations between undercover agents who posed as smugglers and transporters of immigrants and former managers at Tyson poultry plants.
    

Tyson attorneys argued successfully that if the company hired illegal workers, it was because of the huge underground market for phony immigration papers and the government's flawed system of screening immigrants.
    

Agents testified that they delivered 136 illegal immigrants from Mexico and Central America for Tyson employment. Other testimony said the company tried to shield itself by using temporary employment agencies to find workers, mostly illegal immigrants.
   

 Before the case went to trial, four former employees at Tyson's Shelbyville, Tenn., plant sued. The lawsuit by Birda Trollinger, Robert Martinez, Tabetha Edding and Doris Jewell contends the company violated the Racketeer Influenced and Corrupt Organizations Act by knowingly hiring illegal immigrants who were willing to work for wages below those acceptable to Americans.
    

The lawsuit says Tyson relied on a network of recruiters and temporary employment agencies that brought illegal workers into the United States and supplied them with false identification.
  

  Mr. Foster said Tyson employee pay, "probably $8 to $10 an hour," was depressed by the hiring of illegal immigrants.
  

  "We haven't stated exactly" by what amount wages were depressed, he said, adding that that would be determined by "experts."
   

 The eight Tyson plants named in the suit are at Shelbyville; Corydon, Ind.; Gadsden, Ala., Blountsville, Ala., Ashland, Ala.; Sedalia, Mo.; Center, Texas and Glen Allen, Va.