A formulation is presented for evaluating the spectral broadening, due to an extended nonuniform scattering region, of waves scattered from the electron diamagnetic drift waves in a tokamak plasma. The spectral distribution is evaluated numerically and compared with the experimental results obtained in JIPP T-IIU. Good agreement is obtained when the amplitude of the density fluctuation, ñe(r), is assumed to vary parabolically with the radius, just like the local time averaged density. It is also shown that non-uniformity of the plasma parameters in the scattering volume has a significant effect on the apparent form factor, S(k), and on the spatial distribution of the density fluctuations.