The Knights of Malta, the ancient Catholic lay order, is refusing to cooperate with a Vatican investigation into the sacking of a top official over a condom scandal — and is warning its members to toe the line if they choose to speak with investigators.

In a statement released on Tuesday, the Knights called the investigation legally "irrelevant" and aimed at limiting its sovereignty. It insisted that the ousting of its grand chancellor, Albrecht von Boeselager, was an act of internal governance that in no way involves religious superiors.