NEW YORK (AP) ― A bitter contract dispute has led to a lockout of musicians at the New York City Opera, a possible “death knell’’ for a company that’s nurtured such singers as Renee Fleming, Placido Domingo and Beverly Sills.

On Sunday, hours after talks broke down, the cash-strapped company canceled Monday rehearsals for a Feb. 12 opening production of Verdi’s “La Traviata’’ in Brooklyn.

“This is a very sad day for what once was a spectacular cultural icon and for the people who performed its music,’’ said Alan Gordon, national executive director of the American Guild of Musical Artists representing the chorus, stage directors and principal singers.

Local 802 of the American Federation of Musicians represents the orchestra. Both unions have been without a contract since the spring.

Gail Kruvand, chairwoman of the orchestra union’s negotiating committee and its assistant principal bass player, said union members “made a good-faith effort to say that, yes, we are willing to sacrifice for the sake of ensuring that the grand tradition of the City Opera lives on.’’

But she said the company’s rejection of union proposals could be “the death knell for one of New York’s cultural treasures.’’

City Opera is now operating on a shoestring, offering orchestra and chorus members minimum fees for an already abbreviated season.

City Opera moved out of its longtime home at the Lincoln Center for the Performing Arts last year, citing financial troubles, and cut back a schedule of 12 to 16 operas in a season, with a peak of about 130 performances.

In a statement, the company said it had “no choice but to lock out’’ union members because they rejected the company’s economic offer and had threatened to strike when performances began, according to a statement released Sunday. Both labor unions have passed strike-authorization votes.

City Opera General Manager George Steel said his company couldn’t enter rehearsals with a musician strike looming for performances scheduled in February at the Brooklyn Academy of Music, one of the various venues around New York booked for 16 shows of four productions.