We have studied the magnetic properties of a 240 C ion implanted MnGe alloy (100 keV, 2 x 10{sup 16} ions/cm{sup 2}) by means of magneto-optical Kerr effect (MOKE) hysteresis loops taken at different wavelengths in the visible/near-infrared range and at different temperatures (12-180 K). The details of the MOKE response indicates that the magnetic properties of the sample are due to the contribution of multiple magnetic phases. These can be ascribed to the known coexistence of Mn atoms diluted in the mono-crystalline Ge matrix and of amorphous semiconductive Mn-rich precipitates embedded in it. Our results demonstrate that both phases contribute to the ferromagnetic ordering in Mn{sub x}Ge{sub 1-x} magnetic semiconductors. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)