A federal judge has paved the way for a protracted legal struggle between the NFL and its players, rejecting the NFL Players Association's request for immediate free agency for more than 250 players.

U.S. District Judge David Doty refused to grant a preliminary injunction Monday that would have made all veteran players whose contracts expired Feb. 1 free to join any of the 28 NFL teams without the usual player reserve system of compensation and right of first refusal.But, while depriving the players of short-term leverage in their long-simmering battle with management, the judge predicted the union would win a jury trial on its massive antitrust suit against the league, a process that could extend several years.

In his 16-page ruling, Doty said he "finds it probable that the players will prevail at trial and that at least some of the players are likely to sustain irreparable harm if they are not immediately permitted to sign with other NFL clubs."

Doty cited the possibility of "destruction of the competitive balance" of the league and financial losses by teams in ruling that "the potential harm to the owners greatly outweighs that presented to the players."

The suit was filed last Oct. 15, the day the players ended an ill-fated 24-day suit. It asserts that in the absence of a collective bargaining agreement, the league's player reserve system of compensation-first refusal, the college draft and the standard player contract violate federal antitrust laws. The old collective bargaining agreement expired last Aug. 31, about three weeks before the players walked off the job.

"It is very significant that judge Doty found it probable that the players will win in trial," NFLPA Executive Director Gene Upshaw said. "Winning would mean the awarding of treble damages for players who have been illegally damaged by the owners' unlawful continuance of the 1982 agreement. It is too late for the NFL clubs to undo that damage for 1988 free agents, so they face a huge liability in this litigation."

Upshaw said "we are not surprised" that the preliminary injunction was denied and said he will request a expedited trial date.

The Management Council Executive Committee, the powerful policy-making body of the league's labor relations unit, released a statement demanding that the union, which represents about 1,600 NFL players, resume talks for a collective bargaining agreement for the first time since the strike.

"NFL players now face another season with old benefits," the Management Council statement said. "Players deserve the improved benefits that go hand-in-hand with the negotiated settlement of all the interrelated issues. It is time to get out of the media and back to the bargaining table. We believe the NFLPA should resume bargaining at the earliest possible date."

Doty also urged the sides to resolve their long-standing labor differences at the bargaining table.

"By declining to inject itself into the controvery, the court enables the parties to continue negotiating in the stable and familiar environment of the status quo," Doty's ruling states.