Bowing to pressure from allies, Germany's government this year agreed to send Leopard tanks to Ukraine, one of the big ticket items sought by Kyiv as it gears up to mount a counteroffensive against Russian forces.
Duesseldorf-based Rheinmetall makes the cannon of the Leopard 2 while the Munich-based KMW makes its chassis.
A district court in Munich in a statement on Tuesday said KMW was seeking legal protection to prevent Rheinmetall from making statements it saw as "untrue, misleading factual assertions that violate its rights".
Higher defence spending pushed Rheinmetall to record earnings last year and saw the company enter Germany's DAX blue-chip index.
($1 = 0.9106 euros)Writing by Matthias Williams Editing by Alexandra HudsonOur Standards: The Thomson Reuters Trust Principles.