Mikhail Baryshnikov, American Ballet Theatre's artistic director and star dancer, is apparently planning to ask for a four-month leave of absence in order to star in a movie, ABT sources said today.

The report of its star's impending request for a leave comes at a critical time for ABT, the United States' oldest international-level ballet company, which has acknowledged that it is insolvent and torn with internal dissension.

Baryshnikov's personal representative and spokesman, Edgar Vincent, when asked about reports of the film offer, said, "I'm not saying anything."

Originally Baryshnikov had said through a spokesman that he would make a film next summer during ABT's already scheduled two-month layoff. No specifics about the film could be learned. But apparently no contract has been signed, which leaves Baryshnikov free to reject the film offer.

An ABT official said today that Baryshnikov, if he agrees to do the movie, would ask ABT to allow him to depart for Hollywood sometime during the middle of the company's projected eight-week spring season here at Lincoln Center.

Baryshnikov therefore would miss a number of key performances and rehearsals.

ABT's executive committee will meet Thursday afternoon to attempt to deal with the ensemble's lack of funds, the necessity of making personal guarantees on an urgently needed $2 million bank loan, and the specifics of replacing its two top financial executives, who are expected to resign. Later in the day the full board will gather in an emergency session to vote on the executive committee's recommendations.

But even before those meetings begin, a "palace coup" led by a group of dissident board members appears to have succeeded, ABT senior officials confirmed today. That is expected to result in the departures of board chairman Donald Kendall and executive director Herman E. Krawitz.

Kendall, who is also the chief executive of Pepsico, is expected to send his resignation to the board via letter, ABT sources said, and Krawitz is negotiating to withdraw from his executive directorship and become a consultant.

Kendall and Krawitz have been ABT's two chief supporters of Baryshnikov. With both of them apparently departing, ABT sources said Baryshnikov is drafting a "letter of regret" but has decided to continue in his jobs as ABT's star dancer, as a choreographer and as artistic chief--positions for which he is paid a total of almost $400,000 per year.

Current ABT general manager Charles Dillingham and director of media development Rhoda Grauer are expected to assume many of Krawitz's responsibilities.

In addition, legandary former ABT ballerina Nora Kaye, the company's associate artistic director, has resigned from ABT's board of trustees (she has become an honorary trustee) and soon is expected to resign her associate directorship.

Kaye represents one of the last of the old guard of ABT supporters who built the company to the famed ensemble that it is today. Other resignations are expected shortly.

Kaye was also the company's leading representative on the West Coast. She is a movie producer who lives in Los Angeles and is married to film and stage director Herbert Ross (who directed Baryshnikov's only movie, "The Turning Point," for which Baryshnikov received an Academy Award nomination for Best Supporting Actor).

In addition, because of the turmoil at ABT and the uncertainty as to whether its board will agree to make personal guarantees for a $2 million bank loan so ABT will have funds to begin its season (which this year is scheduled to start in Washington in December), the Metropolitan Opera Association has declined to sign a contract with ABT until the upheaval is resolved. ABT, in addition to being the official company of the Kennedy Center, is the resident company of the Metropolitan Opera House.

Because of the unsigned contract, ABT cannot be certain it will have next spring's season at the Met, even though it has already announced the engagement.

Met sources today said their organization hopes to present a settled, properly directed and financially secure ABT at the Met this season, but that the Met is prepared to present other attractions, should ABT be unable to resolve its internal disputes.

Throughout the recent confusing days at ABT, the Met has avoided contacting the ballet company and has said it will not interfere in the troupe's internal affairs. Early this year, however, the Met had warned ABT that the ballet company's artistic decisions were leading to a box-office disaster.