The National Labor Relations Board charged yesterday that the Marval Poultry Co. made illegal payments to its workers to get them to oust a labor union that struck the giant turkey-processing firm last year.

The complaint issued by NLRB regional director Louis J. D'Amico alleges that Marval personnel director Robert A. Wolfe violated labor law in August when he "telephoned employes and solicited their assistance in a campaign to decertify the union, and promised to compensate employes for such assistance."

The Shenandoah Valley company, locked in a bitter ongoing dispute with Local 400 of the United Food and Commercial Workers Union, then "paid employes various sums of money" for assisting in the decertification effort last October, the complaint said. Federal labor law prohibits firms from initiating or encouraging union decertification, which is done by petitions of a majority of a union's members.

Charles O. Strickler, vice president of Rocco Enterprises, Marval's parent firm, yesterday denied the charges and said he believed they would be found false.

The charges, which will be considered by an NLRB administrative law judge at a May 21 hearing, are the latest chapter in a 10-month battle that has drawn national attention between Marval, whose turkey-processing plant near Harrisonburg is the nation's largest, and Local 400, the Washington area's largest local union, with more than 30,000 members.

The strike revolved around union complaints of low pay and poor working conditions, and a company demand to make it easier for workers to quit the union, in line with Virginia's so-called "Right to Work" law, which forbids contracts that require union membership.

If the initial NLRB charge is upheld, the board could order Marval to again recognize the union as the bargaining agent for the firm's 800 production-line workers. Local 400 represented Marval workers for nearly 30 years until October, when the firm withdrew recognition, saying that a majority of employes had petitioned for the decertification. The union complained to the NLRB.

"Our employes decertified the union on Oct. 1 and we are legally bound to comply with our employes' wishes," Strickler said.

"Other complaints by this union have been found groundless, and this will too," said Strickler. Wolfe, a former Virginia prison official whose role as personnel chief has been controversial during the strike, said "the charge is not true at all, and it certainly will be proven when we get to the hearing."

Thomas McNutt, president of the Landover-based union, which has pushed a nationwide boycott of Marval products, said he was pleased with the NLRB complaint, but added that the company could tie up the case for years through legal appeals. "This is a moral victory, and a substantial victory from a propaganda standpoint, but it doesn't mean much" unless the company is made to resume bargaining with the union, he said.

The complaint, which followed several months of NLRB investigation of union allegations, does not specify the amount of alleged payments. But union lawyer Robert Paul said Local 400 obtained affidavits from employes describing company offers to pay $15 for workers to come to the plant early to solicit antiunion petitions, and $15 to stay late for the same purpose. Paul said the union also believes some employes were paid for their signatures.

When the majority of the 500 union members struck, Marval continued production, hiring replacements for strikers. Many strikers subsequently returned to work, while several hundred quit or remained on strike.