The Washington National Opera is accusing the Kennedy Center of failing to return more than $17 million in donor funds, escalating a dispute that followed the end of a 15-year partnership between the two institutions.

In a court filing, the opera company said the money in question came from years of contributions by supporters who specifically intended their gifts to benefit the Washington National Opera and its artistic and educational mission. Those donors, the filing argues, entrusted their contributions to support performances, artists, and community programming carried out by the opera over decades.