  We present the results of spectral fits made to 57 pointed observations of
the Galactic black hole candidate and X-ray transient XTE J1650-500, made with
the Rossi X-ray Timing Explorer in 2001 when the source was in a transition
from the hard state to the soft state. A strong and variable Fe K-alpha
emission line is detected in these spectra. The line flux varies in a
non-linear way with the hard X-ray flux, in apparent contradiction to the
predictions of simple disc reflection models. We observe a change in the
overall trend that coincides with changes in t he continuum X-ray spectrum and
the fast X-ray variability. The Fe-line flux versus hard X-ray flux variations
are consistent with the predictions of reflection models which consider high
disc-ionization states and with a model which considers gravitational
light-bending effects. Indications for an anti-correlation between the Fe-line
flux and the hard X-ray flux in the spectrally hardest observations and weak
variations in the Fe-line energy (as observed with XMM-Newton and BeppoSAX)
slightly favour the light-bending interpretation.
