In a letter to the orchestra musicians, Muti wrote, "I believe that, at the moment there are not the conditions for us to play music together."
A March 11 concert by La Scala Philharmonic had to be canceled because of Muti's refusal to conduct. It is unclear when he might be willing to take up the baton again.
La Scala musicians and Muti have been in conflict since the theater's governors fired general manager Carlo Fontana on February 24. Musicians and La Scala employees feel that Muti undermined Fontana, and imposed his will on theater operations, accusations which Muti denied in a letter to the Italian newspaper Corriere della Sera last week.
Workers have promised to strike for the premiere of every performance at La Scala; the strikes have already caused a number of cancellations, including the premiere of Azio Corghi's Il dissoluto assoluto, a new Don Juan story with a libretto by Jos_ Saramago.
Fontana was replaced with Mauro Meli, La Scala's theater director and Muti's choice for the position.
Milan mayor Gabriele Albertini, the chairman of La Scala's board, has proposed that government commissioners take over the theater's operations, declaring such a drastic option preferable to giving in to the musicians' demands, which included reversing the decision to fire Fontana. (More recently, the musicians have called on Meli to step down voluntarily.)
If the crisis cannot be resolved, Albertini said, Muti should "leave La Scala and go elsewhere. Any theater in the world would welcome him with open arms."