A device for detecting breakage of a gas turbine engine shaft and for reducing the rotational speed of the turbine includes a rotor of a turbine or of a first stage turbine driving the shaft. The rotor has a turbine disk with a rim. A stator that the rotor rotates inside or a nozzle guide vanes assembly of the first turbine stage is provided. A temperature sensor is positioned on the stator or on the nozzle guide vanes assembly, immediately downstream of the rim. The sensor is located to sense temperature on a portion of the stator that contacts the rotor, or on a portion of the nozzle guide vanes assembly that contacts the first stage rotor, in the event of shaft breakage. An engine fuel control member connects to the sensor and can interrupt fuel supply to the engine, when the sensor emits a signal above a predetermined threshold.