Two months ago, the conductor James Levine, having been fired by the Metropolitan Opera for sexual misconduct, sued the company for breach of contract and defamation. Now the Met is suing him back, arguing in court papers filed on Friday that Mr. Levine harmed the company, and detailing previously unreported accusations of sexual harassment and abuse against him.

The filing paints the clearest picture yet of the investigation that led the Met to dismiss Mr. Levine, its longtime music director and its artistic backbone for more than four decades. The company says it found credible evidence that Mr. Levine had “used his reputation and position of power to prey upon and abuse artists,” citing examples of sexual misconduct that it says occurred from the 1970s through 1999, but does not name the victims.

When a 16-year-old artist auditioned for Mr. Levine in 1979, the suit says, Mr. Levine questioned him about his sex life. Two years later, it says, Mr. Levine entered the young man’s dressing room in a bathrobe to discuss an upcoming performance. Mr. Levine made sexual remarks or inappropriately touched the man at least seven times over a period of 12 years, the suit says.

After Mr. Levine offered to drive another singer home from an audition at the Met in 1985, the lawsuit says, he locked the car doors and groped and kissed the man against his will. After the encounter, it says, Mr. Levine placed him in “in a prestigious program” at the Met.

The lawsuit also describes inappropriate conversations that Mr. Levine initiated with another artist in 1989 about masturbation, pornography and penis size, and a failed attempt by Mr. Levine in 1994 to get a man to accompany him to a restroom at the opera house to watch him masturbate.

In addition to serving as the Met’s music director and later music director emeritus, Mr. Levine oversaw the company’s prestigious young artist development program, which can serve as a career springboard. In 1999, the lawsuit says, Mr. Levine inappropriately touched one of its members on his knees, legs and hands. About a year later, it says, he invited the young artist into his dressing room “to engage in sexual activity.”

Lawyers for Mr. Levine denied the Met’s allegations in their own court filing on Friday. “The truth is that Levine did not commit any acts of sexual misconduct against any individuals, much less the unnamed individuals referred to,” his lawyers wrote. “The Met’s so-called ‘investigation’ of Levine’s conduct,” they added, “was nothing more than a pretext for the Met to suspend, fire and defame him.”

The Met’s new filing cites seven accusations of misconduct by Mr. Levine, five of which have not been previously reported. The other two men have already shared their accounts publicly and Mr. Levine has denied their accusations: James Lestock, a cellist who said he was abused for years beginning when he was a student of Mr. Levine’s; and Ashok Pai, who said that he was abused by Mr. Levine beginning when he was 16. Nine men in total have come forward with accusations of harassment or abuse.

The lawyers dispute the Met’s description of Mr. Levine’s relationship with a third person he believes he can identify, the young man who was visited by Mr. Levine in a bathrobe. Their filing describes him as a close personal friend of Mr. Levine’s and says that he did not work at the Met at the time of the incident and that Mr. Levine had more than 140 letters from him. The filing adds that “bathrobes are commonly worn by musical performers backstage in the theater, and there was nothing inappropriate or improper about Levine wearing one.”

Mr. Levine’s suit against the Met says that he “categorically denied having ever been engaged in an abusive sexual relationship.” He has sought at least $5.8 million in damages — his contract included a $400,000 annual salary and a $27,000 fee for each performance — and his suit paints his firing as part of a longstanding effort by Peter Gelb, who became the Met’s general manager in 2006, to oust him from the company.

The Met is now suing Mr. Levine — also for at least $5.8 million — arguing that his misconduct violated his duties to the Met and caused the institution harm. “By engaging in repeated acts of sexual misconduct during his association with the Met,” it says, “including during the period that Levine was responsible for the Young Artist Program, Levine unquestionably violated his duty of loyalty.”

The company suspended Mr. Levine in December, and commissioned an outside investigation into his behavior, after reports appeared in The New York Times and The New York Post detailing accusations by several men who said they had been sexually abused by him decades ago, when they were teenagers or students of his. The Met fired Mr. Levine in March after the investigation found what it called “credible and corroborated evidence of sexual misconduct during his time at the Met, as well as earlier.” A few days later, Mr. Levine sued, accusing the company of defamation and breach of contract.

The Met’s suit says that the company “has and will continue to incur significant reputational and economic harm as a result of the publicity associated with Levine’s misconduct.” The company was already in a difficult financial position before the scandal broke, battling the high costs of putting on grand opera amid a box office slump.

On Friday, Moody’s Investors Service Inc., the credit rating agency, downgraded the Met’s bonds to Baa2 from Baa1, citing its “thin liquidity and the fact that it has not yet been able to reach its endowment fund-raising targets combined with ongoing labor costs pressures and capital needs.” One of the Met’s strengths, it noted, was its strong donor support, which the company relies on.

A version of this article appears in print on , on Page A17 of the New York edition with the headline: Metropolitan Opera Accuses Fired Conductor of Decades of Misconduct. Order Reprints | Today’s Paper | Subscribe