The National Basketball Association filed a lawsuit on Tuesday against the players' union, seeking a ruling that the lockout of players does not violate antitrust laws.

The NBA said the lawsuit, filed in Manhattan Federal Court, arises from the union's threatened use of antitrust litigation to extract a more favorable contract in ongoing negotiations.

"The union's improper threats of antitrust litigation are having a direct, immediate and harmful effect upon the ability of the parties to negotiate a new collective bargaining agreement," the lawsuit said.

The NBA also said on Tuesday that it had filed an unfair labor practice charge against the union before the National Labor Relations Board, saying the players have failed to bargain in good faith.

William Hunter, executive director of the players' association, said in a statement that the NBA's actions "are just another example of their bad-faith bargaining, and we will seek the complete dismissal of the actions as they are totally without merit."

Throughout the negotiations for a new collective bargaining agreement, the NBA said, the players' union has repeatedly threatened to renounce its role as the bargaining representative of the NBA players.

In its lawsuit, the NBA called the threat "an impermissible negotiating tactic" designed only to commence an antitrust challenge to the lockout and gain leverage in contract negotiations.

The NBA contended the same tactic was pursued by the National Football League players' union in its most recent collective bargaining negotiations.