Fifteen players on Spain’s national women’s soccer team have said they will not play under its current coach, sparking a public mutiny that drew a stern rebuke from the Spanish soccer federation.

The 15 players this week wrote identical letters, according to a statement released by the federation on Thursday, in which they threatened to quit the national team unless their coach, Jorge Vilda, was fired. The athletes, according to news reports in Spain, are frustrated at several aspects of Vilda’s approach, and the federation’s statement alluded to those concerns, saying the players had written about the effect of Vilda’s management and coaching style on “their emotional state and their health.”

The federation responded by saying that not only would it not fire Vilda, who has led Spain since 2015, but that the players must apologize for their actions before they will be allowed back on the team.