We present a new design of a scanning force microscope (SFM) for operation at low temperatures in an ultrahigh vacuum (UHV) system. The SFM features an all-fiber interferometer detection mechanism and can be used for contact as well as for noncontact measurements. Cooling is performed in a UHV compatible liquid helium bath cryostat. The design allows in situ cantilever and sample exchange at room temperature; the subsequent transport of the microscope into the cryostat is done by a specially designed transfer mechanism. Atomic resolution images acquired at various temperatures down to 10 K in contact as well as in noncontact mode are shown to demonstrate the performance of the microscope.