LOS ANGELES -- The producer of the "thirtysomething" television series has sued star Timothy Busfield, claiming the actor has threatened to boycott filming of the show's fourth season unless he gets a raise.

The suit, filed Wednesday in Los Angeles Superior Court by MGM-UA Television Production Group Inc., alleges that Busfield is refusing to report for work on Aug. 3, the start of filming for the fall season. It asks a judge to order him to return to work.

The suit alleges that Busfield wants to be paid $36,375 per episode. MGM-UA said it offered the red-haired actor $28,750 for each 1990-91 installment of the popular series.

"MGM has failed to live up to their agreement with Mr. Busfield," Edward Burg, the actor's attorney, responded yesterday. "They are trying to coerce him into returning to work and he won't be coerced."

Burg declined to comment further.

The suit claims that Busfield, who also has appeared in feature films including "Field of Dreams," has breached his five-year contract by threatening to stay off the set. It seeks unspecified compensatory and punitive damages.

It also seeks to bar the actor, who currently is starring on Broadway in "A Few Good Men," from appearing in movies, television productions and stage plays until the dispute is resolved.

In opposition papers, Busfield's attorney alleged that such a court-ordered injunction would prohibit the actor from earning a living.

Busfield portrays Elliot Weston in the ABC drama about the everyday lives of a group of friends approaching middle age in Philadelphia. Busfield's character is married to Nancy (played by Patricia Wettig), whose battle with cancer is expected to be a crucial aspect of the new season.

ABC, "thirtysomething" supervising producer Scott Winant and Busfield's agent all declined to comment yesterday.