Opera star Plácido Domingo was placed under investigation Tuesday by the Los Angeles Opera, which he helped found and has led since 2003, after The Associated Press reported that multiple women had accused him of sexual harassment over the years.

Domingo denied the allegations, which shook the opera world, where he remains, at 78, one of the industry’s biggest luminaries. The Philadelphia Orchestra withdrew its invitation for Domingo to sing at its opening night gala next month; the Metropolitan Opera in New York City, where Domingo is scheduled to star in Verdi’s “Macbeth” next month opposite soprano Anna Netrebko, said it would await the results of the Los Angeles Opera’s investigation “before making any final decisions about Mr. Domingo’s ultimate future at the Met.”

The Associated Press reported that eight singers and a dancer had given accounts of being harassed by Domingo in a series of encounters beginning in the late 1980s.

Domingo said in a statement that “the allegations from these unnamed individuals dating back as many as 30 years are deeply troubling, and as presented, inaccurate” but added that “it is painful to hear that I may have upset anyone or made them feel uncomfortable — no matter how long ago and despite my best intentions.”

He added that “the rules and standards by which we are — and should be — measured against today are very different than they were in the past” and pledged to hold himself “to the highest standards.”

The Los Angeles Opera said it would engage an outside counsel to investigate the allegations against Domingo.

The women who spoke to the AP, all but one of whom were quoted anonymously, said Domingo had used his power to pursue them sexually — calling them repeatedly and making dates, often under the guise of offering professional advice.